This came up in #14113. getlocale(LC_ALL) is documented to fail, at
least that's how I read this:

   "category may be one of the LC_* values except LC_ALL."


But in fact getlocale(LC_ALL) works if there is no semicolon in the
locale name:

>>> getlocale(LC_ALL)
('en_US', 'ISO8859-1')


I would prefer if getlocale(LC_ALL) fails consistently. If that's
not possible, then this is a documentation issue.