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Issue 29571: test_re is failing when local is set for `en_IN`

Created on 2017-02-15 17:29 by jaysinh.shukla, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (37) msg287867 - (view) Author: Jaysinh shukla (jaysinh.shukla) * Date: 2017-02-15 17:29
Description:
    A test case is failing while running `./python -m test -v test_re`.

Traceback:
$>./python -m test -v test_re
== CPython 3.7.0a0 (default, Feb 15 2017, 22:28:32) [GCC 5.4.0 20160609]
==   Linux-4.4.0-62-generic-x86_64-with-debian-stretch-sid little-endian
==   hash algorithm: siphash24 64bit
==  cwd: /home/bigj/Jaysinh/cpython_git/cpython/build/test_python_613
==  encodings: locale=UTF-8, FS=utf-8
Testing with flags: sys.flags(debug=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=0, verbose=0, bytes_warning=0, quiet=0, hash_randomization=1, isolated=0)
Run tests sequentially
0:00:00 [1/1] test_re
test_re_benchmarks (test.test_re.ExternalTests)
re_tests benchmarks ... ok
test_re_tests (test.test_re.ExternalTests)
re_tests test suite ... ok
test_overlap_table (test.test_re.ImplementationTest) ... ok
test_bytes (test.test_re.PatternReprTests) ... ok
test_inline_flags (test.test_re.PatternReprTests) ... ok
test_locale (test.test_re.PatternReprTests) ... ok
test_long_pattern (test.test_re.PatternReprTests) ... ok
test_multiple_flags (test.test_re.PatternReprTests) ... ok
test_quotes (test.test_re.PatternReprTests) ... ok
test_single_flag (test.test_re.PatternReprTests) ... ok
test_unicode_flag (test.test_re.PatternReprTests) ... ok
test_unknown_flags (test.test_re.PatternReprTests) ... ok
test_without_flags (test.test_re.PatternReprTests) ... ok
test_anyall (test.test_re.ReTests) ... ok
test_ascii_and_unicode_flag (test.test_re.ReTests) ... ok
test_backref_group_name_in_exception (test.test_re.ReTests) ... ok
test_basic_re_sub (test.test_re.ReTests) ... ok
test_big_codesize (test.test_re.ReTests) ... ok
test_bigcharset (test.test_re.ReTests) ... ok
test_bug_113254 (test.test_re.ReTests) ... ok
test_bug_114660 (test.test_re.ReTests) ... ok
test_bug_117612 (test.test_re.ReTests) ... ok
test_bug_1661 (test.test_re.ReTests) ... ok
test_bug_16688 (test.test_re.ReTests) ... ok
test_bug_20998 (test.test_re.ReTests) ... ok
test_bug_2537 (test.test_re.ReTests) ... ok
test_bug_29444 (test.test_re.ReTests) ... ok
test_bug_3629 (test.test_re.ReTests) ... ok
test_bug_418626 (test.test_re.ReTests) ... ok
test_bug_448951 (test.test_re.ReTests) ... ok
test_bug_449000 (test.test_re.ReTests) ... ok
test_bug_449964 (test.test_re.ReTests) ... ok
test_bug_462270 (test.test_re.ReTests) ... ok
test_bug_527371 (test.test_re.ReTests) ... ok
test_bug_581080 (test.test_re.ReTests) ... ok
test_bug_612074 (test.test_re.ReTests) ... ok
test_bug_6509 (test.test_re.ReTests) ... ok
test_bug_6561 (test.test_re.ReTests) ... ok
test_bug_725106 (test.test_re.ReTests) ... ok
test_bug_725149 (test.test_re.ReTests) ... ok
test_bug_764548 (test.test_re.ReTests) ... ok
test_bug_817234 (test.test_re.ReTests) ... ok
test_bug_926075 (test.test_re.ReTests) ... ok
test_bug_931848 (test.test_re.ReTests) ... ok
test_bytes_str_mixing (test.test_re.ReTests) ... ok
test_category (test.test_re.ReTests) ... ok
test_character_set_errors (test.test_re.ReTests) ... ok
test_compile (test.test_re.ReTests) ... ok
test_constants (test.test_re.ReTests) ... ok
test_dealloc (test.test_re.ReTests) ... ok
test_debug_flag (test.test_re.ReTests) ... ok
test_dollar_matches_twice (test.test_re.ReTests)
$ matches the end of string, and just before the terminating ... ok
test_empty_array (test.test_re.ReTests) ... ok
test_enum (test.test_re.ReTests) ... ok
test_error (test.test_re.ReTests) ... ok
test_expand (test.test_re.ReTests) ... ok
test_finditer (test.test_re.ReTests) ... ok
test_flags (test.test_re.ReTests) ... ok
test_getattr (test.test_re.ReTests) ... ok
test_getlower (test.test_re.ReTests) ... ok
test_group (test.test_re.ReTests) ... ok
test_group_name_in_exception (test.test_re.ReTests) ... ok
test_groupdict (test.test_re.ReTests) ... ok
test_ignore_case (test.test_re.ReTests) ... ok
test_ignore_case_range (test.test_re.ReTests) ... ok
test_ignore_case_set (test.test_re.ReTests) ... ok
test_inline_flags (test.test_re.ReTests) ... ok
test_issue17998 (test.test_re.ReTests) ... ok
test_keep_buffer (test.test_re.ReTests) ... ok
test_keyword_parameters (test.test_re.ReTests) ... ok
test_large_search (test.test_re.ReTests) ... ok
test_large_subn (test.test_re.ReTests) ... ok
test_locale_caching (test.test_re.ReTests) ... skipped 'test needs en_US.iso88591 locale'
test_locale_flag (test.test_re.ReTests) ... FAIL
test_lookahead (test.test_re.ReTests) ... ok
test_lookbehind (test.test_re.ReTests) ... ok
test_match_getitem (test.test_re.ReTests) ... ok
test_match_repr (test.test_re.ReTests) ... ok
test_misc_errors (test.test_re.ReTests) ... ok
test_multiple_repeat (test.test_re.ReTests) ... ok
test_not_literal (test.test_re.ReTests) ... ok
test_nothing_to_repeat (test.test_re.ReTests) ... ok
test_other_escapes (test.test_re.ReTests) ... ok
test_pattern_compare (test.test_re.ReTests) ... ok
test_pattern_compare_bytes (test.test_re.ReTests) ... ok
test_pickling (test.test_re.ReTests) ... ok
test_qualified_re_split (test.test_re.ReTests) ... ok
test_qualified_re_sub (test.test_re.ReTests) ... ok
test_re_escape (test.test_re.ReTests) ... ok
test_re_escape_byte (test.test_re.ReTests) ... ok
test_re_escape_non_ascii (test.test_re.ReTests) ... ok
test_re_escape_non_ascii_bytes (test.test_re.ReTests) ... ok
test_re_findall (test.test_re.ReTests) ... ok
test_re_fullmatch (test.test_re.ReTests) ... ok
test_re_groupref (test.test_re.ReTests) ... ok
test_re_groupref_exists (test.test_re.ReTests) ... ok
test_re_groupref_overflow (test.test_re.ReTests) ... ok
test_re_match (test.test_re.ReTests) ... ok
test_re_split (test.test_re.ReTests) ... ok
test_re_subn (test.test_re.ReTests) ... ok
test_repeat_minmax (test.test_re.ReTests) ... ok
test_repeat_minmax_overflow (test.test_re.ReTests) ... ok
test_repeat_minmax_overflow_maxrepeat (test.test_re.ReTests) ... ok
test_scanner (test.test_re.ReTests) ... ok
test_scoped_flags (test.test_re.ReTests) ... ok
test_search_coverage (test.test_re.ReTests) ... ok
test_search_dot_unicode (test.test_re.ReTests) ... ok
test_search_star_plus (test.test_re.ReTests) ... ok
test_special_escapes (test.test_re.ReTests) ... ok
test_sre_byte_class_literals (test.test_re.ReTests) ... ok
test_sre_byte_literals (test.test_re.ReTests) ... ok
test_sre_character_class_literals (test.test_re.ReTests) ... ok
test_sre_character_literals (test.test_re.ReTests) ... ok
test_stack_overflow (test.test_re.ReTests) ... ok
test_string_boundaries (test.test_re.ReTests) ... ok
test_sub_template_numeric_escape (test.test_re.ReTests) ... ok
test_symbolic_groups (test.test_re.ReTests) ... ok
test_symbolic_refs (test.test_re.ReTests) ... ok
test_unlimited_zero_width_repeat (test.test_re.ReTests) ... ok
test_weakref (test.test_re.ReTests) ... ok

======================================================================
FAIL: test_locale_flag (test.test_re.ReTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/bigj/Jaysinh/cpython_git/cpython/Lib/test/test_re.py", line 1422, in test_locale_flag
    self.assertTrue(pat.match(bletter))
AssertionError: None is not true

----------------------------------------------------------------------
Ran 120 tests in 2.079s

FAILED (failures=1, skipped=1)
test test_re failed
test_re failed

1 test failed:
    test_re

Total duration: 2 sec
Tests result: FAILURE

Local value:
$>locale
LANG=en_IN
LANGUAGE=en_IN:en
LC_CTYPE="en_IN"
LC_NUMERIC="en_IN"
LC_TIME="en_IN"
LC_COLLATE="en_IN"
LC_MONETARY="en_IN"
LC_MESSAGES="en_IN"
LC_PAPER="en_IN"
LC_NAME="en_IN"
LC_ADDRESS="en_IN"
LC_TELEPHONE="en_IN"
LC_MEASUREMENT="en_IN"
LC_IDENTIFICATION="en_IN"
LC_ALL=

Operating system: Ubuntu 16.04 LTS(64 bit)
msg287879 - (view) Author: Matthew Barnett (mrabarnett) * Date: 2017-02-15 18:56
I'm just wondering whether the problem is just due to the locale's encoding being UTF-8. The locale support in re really only works with encodings that use 1 byte/character.
msg287880 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-02-15 19:03
Locale encoding is ISO8859-1. This test is skipped on non 8-bit locale.

This is a problem with tests, not with the re module. I don't have a solution.
msg287882 - (view) Author: Matthew Barnett (mrabarnett) * Date: 2017-02-15 19:25
The report says "==  encodings: locale=UTF-8, FS=utf-8".

It says that "test_locale_caching" was skipped, but also that "test_locale_flag" failed.
msg287893 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-02-15 22:57
Good point. The test used locale.getlocale() and it returned returned ('en_IN', 'ISO8859-1').

Following patch makes the test using locale.getpreferredencoding(False), the same encoding as was reported at the header of test report.
msg287894 - (view) Author: STINNER Victor (vstinner) * Date: 2017-02-15 22:58
> Following patch ...

Seriously? Not a GitHub pull request? ;-) (old habit?)
msg287933 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-02-16 12:05
> Seriously? Not a GitHub pull request? ;-) (old habit?)

I'm not experienced with git, and devguide still looks not ready.
msg288056 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-02-18 05:04
I have a few folks hitting this at the PyCon Pune sprints, so I'm going to apply Serhiy's patch :)
msg288065 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-02-18 08:54
Looking into this at the PyCon Pune sprints, the problem appears to be arising due to the following difference in behaviour when the unqualifed `en_IN` locale is set:

$ LANG=en_IN.UTF-8 python3 -c "import locale; print(locale.getlocale(locale.LC_CTYPE), locale.getpreferredencoding(False), sep='\n')"
('en_IN', 'UTF-8')
UTF-8

$ LANG=en_IN python3 -c "import locale; print(locale.getlocale(locale.LC_CTYPE), locale.getpreferredencoding(False), sep='\n')"
('en_IN', 'ISO8859-1')                                                                                                       
UTF-8

re.LOCALE is presumably picking up the "UTF-8" rather than the "ISO8859-1", and hence the test is failing.
msg288068 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-02-18 09:25
Yes, please push it Nick.
msg288069 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-02-18 09:31
New changeset ace5c0fdd9b962e6e886c29dbcea72c53f051dc4 by GitHub in branch 'master':
bpo-29571: Use correct locale encoding in test_re (#149)
https://github.com/python/cpython/commit/ace5c0fdd9b962e6e886c29dbcea72c53f051dc4
msg288101 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-02-19 04:33
New changeset 0683d6889bd4430599d22e12e201b8e9c45be5a2 by GitHub in branch '3.6':
[3.6] bpo-29571: Use correct locale encoding in test_re (#149) (#153)
https://github.com/python/cpython/commit/0683d6889bd4430599d22e12e201b8e9c45be5a2
msg288102 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-02-19 04:33
New changeset 760f596b6a4b5514afe35e521621f484aef35413 by GitHub in branch '3.5':
[3.5] bpo-29571: Use correct locale encoding in test_re (#149) (#154)
https://github.com/python/cpython/commit/760f596b6a4b5514afe35e521621f484aef35413
msg289054 - (view) Author: Zachary Ware (zach.ware) * Date: 2017-03-06 01:34
This seems to have broken test_re on Windows, see https://ci.appveyor.com/project/python/cpython/build/3.7.0a0.1

I found this change to be the culprit via git bisect, unfortunately we didn't have any working CI on Windows (buildbots were otherwise broken) at the time this was merged.
msg289071 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-06 07:52
Yep, I think we should merge https://github.com/python/cpython/pull/422 and revert ncoghlan's change.
msg289072 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-03-06 07:54
I'm not sure this will help on Windows.
msg289073 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * Date: 2017-03-06 07:55
And I don't understand why my fix doesn't work on Windows.
msg289074 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-06 07:55
But the test was never broken on windows.

On Sun, Mar 5, 2017, at 23:54, Serhiy Storchaka wrote:
> 
> Serhiy Storchaka added the comment:
> 
> I'm not sure this will help on Windows.
> 
> ----------
> 
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue29571>
> _______________________________________
msg289075 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-06 07:55
getpreferredencoding() takes a completely different path on windows
(returns a codepage) and isn't related to the C locale.
msg289076 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-03-06 07:58
I'm with Serhiy on this one: if the "re" module isn't using locale.getpreferredencoding(), then there's something odd going on.

It just sounds like the disconnect on Windows is the opposite of the one we hit on Linux without Benjamin's patch, perhaps due to the UTF-8 mode changes - it wouldn't surprise me to learn that the re module is still using mbcs there instead of utf-8.
msg289077 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-06 08:01
I don't see what's odd about it. re.LOCALE uses the C locale, which one
obtains from locale.getlocale(). getpreferredencoding() is not
documented to have anything to do with the C locale, and indeed on
Windows it may be completely different.
msg289118 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2017-03-06 15:52
Thanks for the explanation - given that, I agree that simply reverting the attempted test-based fix and instead relying on the issue 20087 updates is the way to go.
msg290268 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-24 22:42
New changeset 6a4b04cd337347d074ae0140fb13dca5bd4b11ef by Benjamin Peterson in branch '3.6':
Revert "bpo-29571: Use correct locale encoding in test_re (#149)" (#554) (#555)
https://github.com/python/cpython/commit/6a4b04cd337347d074ae0140fb13dca5bd4b11ef
msg290269 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-24 22:42
New changeset 312f7dfb7c669fcfc43020951b7f8ff521200ad7 by Benjamin Peterson in branch '3.5':
Revert "bpo-29571: Use correct locale encoding in test_re (#149)" (#554) (#556)
https://github.com/python/cpython/commit/312f7dfb7c669fcfc43020951b7f8ff521200ad7
msg290272 - (view) Author: Benjamin Peterson (benjamin.peterson) * Date: 2017-03-24 22:42
New changeset 21a74312f2d1ddee71fade709af49d078085ec30 by Benjamin Peterson in branch 'master':
Revert "bpo-29571: Use correct locale encoding in test_re (#149)" (#554)
https://github.com/python/cpython/commit/21a74312f2d1ddee71fade709af49d078085ec30
msg310947 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2018-01-28 14:01
Hmm, even though we reverted the original test_re based change, and the initial attempted fix for bpo-20087 was also reverted, I'm still not currently seeing the failure for:

    LANG=en_IN.utf8 ./python -m test -v test_re

I do have the locale installed, so it's not a result of falling back to the C locale and that getting coerced to C.UTF-8:

    $ LANG=en_IN.utf8 locale -k currency_symbol
    currency_symbol="₹"

Jaysinh, are you still seeing this test failure on a fresh checkout?
msg310948 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2018-01-28 14:15
Hmm, this actually works for me on Fedora 27 even if I go back to 1b3d88eb33085e90af729c4c2f78b5ba1b942b1e, the commit just before the initially merged (and subsequently reverted) test change above.

Unassigning, since I can't readily reproduce it myself.
msg311074 - (view) Author: Jaysinh shukla (jaysinh.shukla) * Date: 2018-01-29 07:00
Hello Nick,

    At the devsprints of Pycon India 2017, a few participants were facing this bug. They all were from the Ubuntu land. I have switched to Gentoo distro. I am not facing this bug, but let me confirm from any Ubuntu user. Thanks
msg311076 - (view) Author: Alyssa Coghlan (ncoghlan) * Date: 2018-01-29 07:21
I've also added Matthias and Barry to the cc list, in case this does turn out to be a Debian or Ubuntu specific quirk.

Restating the problem, the issue is that test_locale_flag in test_re may fail for at least the en_IN locale, and we're not sure yet whether that's a test bug, a locale module bug, or a distro bug:

    LANG=en_IN ./python -m test -v test_re

We've only confirmed it on Ubuntu so far though - I haven't been able to reproduce it on Fedora, and Jaysinh hasn't been able to reproduce it since switching to Gentoo.
msg336826 - (view) Author: Karthikeyan Singaravelan (xtreak) * Date: 2019-02-28 11:23
Similar issue reported on debian9.8 stretch with python 3.7.2 and en_IN : issue36134
msg336855 - (view) Author: STINNER Victor (vstinner) * Date: 2019-02-28 17:34
Ah, I can reproduce the bug on Fedora 29 using "LANG=en_IN ./python -m test -v test_re".

The problem is that locale.getlocale() is not reliable: it pretends that the locale encoding is ISO8859-1, whereas the real encoding is UTF-8:

$ LANG=en_IN ./python 
Python 3.8.0a2+ (heads/master:4cbea518a0, Feb 28 2019, 18:19:44) 
>>> chr(224).encode('ISO8859-1')
b'\xe0'
>>> import _testcapi
>>> _testcapi.DecodeLocaleEx(b'\xe0', 0, 'strict')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: decode error: pos=0, reason=decoding error

>>> import locale

# Wrong encoding
>>> locale.getlocale(locale.LC_CTYPE)
('en_IN', 'ISO8859-1')
>>> locale.setlocale(locale.LC_CTYPE, None)
'en_IN'
>>> locale._parse_localename('en_IN')
('en_IN', 'ISO8859-1')

# Real encoding
>>> locale.getpreferredencoding()
'UTF-8'
>>> locale.nl_langinfo(locale.CODESET)
'UTF-8'


Attached PR 12099 fix the issue.
msg336877 - (view) Author: STINNER Victor (vstinner) * Date: 2019-02-28 23:05
> This seems to have broken test_re on Windows, see https://ci.appveyor.com/project/python/cpython/build/3.7.0a0.1

It seems like the ANSI code page is 1252 ("cp1252").

== CPython 3.7.0a0 (master:d31b28e16a2387d0251df948ef5d1b33d4357652, Mar 5 2017, 21:47:06) [MSC v.1900 32 bit (Intel)]
==   Windows-2012ServerR2-6.3.9600-SP0 little-endian
==   hash algorithm: siphash24 32bit
==  cwd: C:\projects\cpython\build\test_python_1844
==  encodings: locale=cp1252, FS=utf-8
Testing with flags: sys.flags(debug=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=1, verbose=0, bytes_warning=2, quiet=0, hash_randomization=1, isolated=0)
Using random seed 5949816

...

FAIL: test_locale_flag (test.test_re.ReTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\projects\cpython\lib\test\test_re.py", line 1422, in test_locale_flag
    self.assertTrue(pat.match(bletter))
AssertionError: None is not true

> getpreferredencoding() takes a completely different path on windows
> (returns a codepage) and isn't related to the C locale.

On my Windows 10 with Python 3.8, getpreferredencoding() (and getpreferredencoding(False)) returns "cp1252", getlocale(LC_CTYPE)[1] returns "1252". Python has an alias "1252" for "cp1252".

On Windows, getpreferredencoding() is implemented as _locale._getdefaultlocale()[1]. _getdefaultlocale()[1] is implemented with:

    PyOS_snprintf(encoding, sizeof(encoding), "cp%d", GetACP());

At the end, it's the ANSI code page (1252).

--

I don't understand how the change ace5c0fdd9b962e6e886c29dbcea72c53f051dc4 introduced a regression. And so I don't understand how commit 21a74312f2d1ddee71fade709af49d078085ec30 (revert) could fix anything.

--

On my PR 12099, two Windows CI run and both succeeded:

* AppVeyor: pythoninfo says "locale.encoding: cp1252"
  https://ci.appveyor.com/project/python/cpython/builds/22726025
* Windows PR Tests on Azure Pipeline: pythoninfo also says "locale.encoding: cp1252"

When the change ace5c0fdd9b962e6e886c29dbcea72c53f051dc4 was merged, Python had no working Windows CI. Things evolved at lot in the meanwhile.

I also tested manually my PR 12099 on my Windows 10 VM which also uses cp1252: test_re pass.

--

re.LOCALE flag of re.compile() for a bytes pattern uses the following function of Modules/_sre.c:

LOCAL(int)
char_loc_ignore(SRE_CODE pattern, SRE_CODE ch)
{
    return ch == pattern
        || (SRE_CODE) sre_lower_locale(ch) == pattern
        || (SRE_CODE) sre_upper_locale(ch) == pattern;
}
msg336878 - (view) Author: STINNER Victor (vstinner) * Date: 2019-02-28 23:08
New changeset ab71f8b793f7b42853ccd2a127ae7720adc5bcb4 by Victor Stinner in branch 'master':
bpo-29571: Fix test_re.test_locale_flag() (GH-12099)
https://github.com/python/cpython/commit/ab71f8b793f7b42853ccd2a127ae7720adc5bcb4
msg336883 - (view) Author: STINNER Victor (vstinner) * Date: 2019-03-01 01:13
AppVeyor failed on the backport to Python 3.7 of my fix: PR 12108.

Ok, now I understand the bug in Python 3.7. locale.getlocale(locale.LC_CTYPE)[1] returns None because Python doesn't set LC_CTYPE to the user preferred locale. I'm not sure of which locale is used in practice in that case, but at least I can say that None is not the expected encoding name... str.encode() and bytes.decode() use UTF-8 when None is passed as the encoding. locale.getpreferredencoding() returns 'cp1252' which is the ANSI code page.

Python 3.8 is different. In bpo-34485, I modified Python 3.8 to set LC_CTYPE locale to the user preference (ANSI code page):
---
commit 177d921c8c03d30daa32994362023f777624b10d
Author: Victor Stinner <vstinner@redhat.com>
Date:   Wed Aug 29 11:25:15 2018 +0200

    bpo-34485, Windows: LC_CTYPE set to user preference (GH-8988)
    
    On Windows, the LC_CTYPE is now set to the user preferred locale at
    startup: _Py_SetLocaleFromEnv(LC_CTYPE) is now called during the
    Python initialization. Previously, the LC_CTYPE locale was "C" at
    startup, but changed when calling setlocale(LC_CTYPE, "") or
    setlocale(LC_ALL, "").
    
    pymain_read_conf() now also calls _Py_SetLocaleFromEnv(LC_CTYPE) to
    behave as _Py_InitializeCore(). Moreover, it doesn't save/restore the
    LC_ALL anymore.
    
    On Windows, standard streams like sys.stdout now always use
    surrogateescape error handler by default (ignore the locale).
---
msg337185 - (view) Author: STINNER Victor (vstinner) * Date: 2019-03-05 12:34
I wrote C and Python code to check what is the effective encoding used by the LC_CTYPE locale before setlocale(LC_CTYPE, "") is called on Python 3.7. Result: Windows uses the Latin1 encoding.

See attached files: _testcapi.patch + loc.py produced loc.log (output).
msg337200 - (view) Author: STINNER Victor (vstinner) * Date: 2019-03-05 15:17
New changeset 279657bac2856039ba422c18a3d7f227b455e9d6 by Victor Stinner in branch '3.7':
[3.7] bpo-29571: Fix test_re.test_locale_flag() (GH-12178)
https://github.com/python/cpython/commit/279657bac2856039ba422c18a3d7f227b455e9d6
msg337204 - (view) Author: STINNER Victor (vstinner) * Date: 2019-03-05 15:26
I don't understand the relationship with bpo-20087, so I removed the dependency.

I fixed test_re in 3.7 and master branches. I close the issue.
History Date User Action Args 2022-04-11 14:58:43adminsetgithub: 73757 2019-10-24 10:46:11vstinnerlinkissue32080 superseder 2019-03-05 15:26:32vstinnersetstatus: open -> closed
versions: + Python 3.8, - Python 3.5, Python 3.6
messages: + msg337204

dependencies: - Mismatch between glibc and X11 locale.alias
resolution: fixed
stage: patch review -> resolved

2019-03-05 15:17:45vstinnersetmessages: + msg337200 2019-03-05 12:44:52vstinnersetpull_requests: + pull_request12173 2019-03-05 12:34:33vstinnersetfiles: + _testcapi.patch 2019-03-05 12:34:26vstinnersetfiles: + loc.log 2019-03-05 12:34:20vstinnersetfiles: + loc.py

messages: + msg337185

2019-03-01 01:13:06vstinnersetmessages: + msg336883 2019-02-28 23:08:30miss-islingtonsetpull_requests: + pull_request12115 2019-02-28 23:08:09vstinnersetmessages: + msg336878 2019-02-28 23:05:44vstinnersetmessages: + msg336877 2019-02-28 17:34:31vstinnersetmessages: + msg336855 2019-02-28 17:34:12vstinnersetstage: patch review
pull_requests: + pull_request12106 2019-02-28 12:55:55serhiy.storchakalinkissue36134 superseder 2019-02-28 11:23:44xtreaksetnosy: + xtreak
messages: + msg336826
2018-01-29 07:21:06ncoghlansetnosy: + barry, doko
messages: + msg311076
2018-01-29 07:00:04jaysinh.shuklasetmessages: + msg311074 2018-01-28 14:15:37ncoghlansetassignee: ncoghlan ->
messages: + msg310948 2018-01-28 14:01:10ncoghlansetmessages: + msg310947 2017-07-12 21:03:59Naman-Bhallasetnosy: + Naman-Bhalla
2017-07-12 20:07:31Naman-Bhallasetpull_requests: + pull_request2751 2017-04-01 05:49:51serhiy.storchakasetpull_requests: - pull_request1096 2017-03-31 16:36:37dstufftsetpull_requests: + pull_request1096 2017-03-24 22:42:25benjamin.petersonsetmessages: + msg290272 2017-03-24 22:42:10benjamin.petersonsetmessages: + msg290269 2017-03-24 22:42:04benjamin.petersonsetmessages: + msg290268 2017-03-08 06:51:44benjamin.petersonsetpull_requests: + pull_request457 2017-03-08 06:51:41benjamin.petersonsetpull_requests: + pull_request456 2017-03-08 06:07:19benjamin.petersonsetpull_requests: + pull_request455 2017-03-06 15:52:28ncoghlansetmessages: + msg289118 2017-03-06 09:41:12serhiy.storchakasetdependencies: + Mismatch between glibc and X11 locale.alias 2017-03-06 08:01:39benjamin.petersonsetmessages: + msg289077 2017-03-06 07:58:37ncoghlansetmessages: + msg289076 2017-03-06 07:55:55benjamin.petersonsetmessages: + msg289075 2017-03-06 07:55:21benjamin.petersonsetmessages: + msg289074 2017-03-06 07:55:14serhiy.storchakasetmessages: + msg289073 2017-03-06 07:54:36serhiy.storchakasetmessages: + msg289072 2017-03-06 07:52:43benjamin.petersonsetnosy: + benjamin.peterson
messages: + msg289071
2017-03-06 06:09:41serhiy.storchakasetstatus: closed -> open

nosy: + steve.dower, paul.moore, tim.golden
components: + Windows
resolution: fixed -> (no value)
stage: resolved -> (no value)

2017-03-06 01:34:31zach.waresetnosy: + zach.ware
messages: + msg289054
2017-03-03 07:51:48benjamin.petersonsetpull_requests: + pull_request352 2017-02-19 04:35:03ncoghlansetstatus: open -> closed
resolution: fixed
stage: patch review -> resolved 2017-02-19 04:33:52ncoghlansetmessages: + msg288102 2017-02-19 04:33:37ncoghlansetmessages: + msg288101 2017-02-18 10:45:14ncoghlansetpull_requests: + pull_request118 2017-02-18 10:44:50ncoghlansetpull_requests: + pull_request117 2017-02-18 09:31:25ncoghlansetmessages: + msg288069 2017-02-18 09:25:58serhiy.storchakasetmessages: + msg288068 2017-02-18 09:19:08ncoghlansetpull_requests: + pull_request112 2017-02-18 08:54:00ncoghlansetmessages: + msg288065 2017-02-18 05:04:15ncoghlansetassignee: serhiy.storchaka -> ncoghlan

messages: + msg288056
nosy: + ncoghlan

2017-02-16 12:05:04serhiy.storchakasetmessages: + msg287933 2017-02-15 22:58:46vstinnersetmessages: + msg287894 2017-02-15 22:57:27serhiy.storchakasetfiles: + test_re_locale_flag.patch
keywords: + patch
messages: + msg287893

stage: patch review

2017-02-15 19:25:47mrabarnettsetmessages: + msg287882 2017-02-15 19:03:27serhiy.storchakasetmessages: + msg287880
components: + Tests
versions: + Python 3.5, Python 3.6 2017-02-15 18:56:16mrabarnettsetmessages: + msg287879 2017-02-15 18:02:04serhiy.storchakasetassignee: serhiy.storchaka

type: behavior
nosy: + serhiy.storchaka

2017-02-15 17:41:28vstinnersetnosy: + vstinner
2017-02-15 17:29:11jaysinh.shuklacreate