The Wayback Machine - https://web.archive.org/web/20121025045402/http://docs.python.org:80/devguide/
Here is a list of the basic steps necessary to get set up and make a patch:
Get a clone of CPython with hg clone http://hg.python.org/cpython.
On UNIX, run ./configure --with-pydebug && make -j2 to build Python.
On Windows, load the project file PCbuild\pcbuild.sln in Visual Studio, select , and .
Run the tests with ./python -m test -j3 (use ./python.exe on most Mac OS X systems and PCbuild\python_d.exe on Windows; replace test with test.regrtest for 2.7).
Make the patch.
Submit it to the issue tracker.
Improving Python’s code, documentation and tests are ongoing tasks that are never going to be “finished”, as Python operates as part of an ever-evolving system of technology. An even more challenging ongoing task than these necessary maintenance activities is finding ways to make Python, in the form of the standard library and the language definition, an even better tool in a developer’s toolkit.
While these kinds of change are much rarer than those described above, they do happen and that process is also described as part of this guide:
Also refer to Where should I suggest new features and language changes? in the FAQ.
This guide is specifically for contributing to the Python reference interpreter, also known as CPython (while most of the standard library is written in Python, the interpreter core is written in C and integrates most easily with the C and C++ ecosystems).
There are other Python implementations, each with a different focus. Like CPython, they always have more things they would like to do than they have developers to work on them. Some major example that may be of interest are:
PEPs (Python Enhancement Proposals)
Anyone can clone the sources for this guide. See Helping with the Developer’s Guide.