Version doesn't include git commit hash when installed via "pip3 install ."

[gvanrossum]

When running mypy directly out of the git repo, the version (reported by -V or --version) includes the git commit hash. It would be nice if it was also included when mypy was installed directly from the repo, e.g. using pip3 install . or perhaps via pip3 install git+git://github.com/python/mypy.git. However we should make sure that when we actually build a distribution file, that file only includes the base version. (Or perhaps only/exactly when the HEAD revision matches a tag whose name matches the base version?)

(See also PR #2452.)

[gvanrossum]

Note that the version is especially important for -i mode, since the cache cannot be trusted when a different version is installed.

Also note that installing from a git-labeled version should not show the commit hash but installing from something intermediate should always show the commit hash. Or something like that. The idea is that when we build a distribution and push it to PyPI it should not have the commit hash in the version but when we install locally (e.g. using pip3 install -U .) the commit hash should be included.

[pkch]

To clarify, as of right now:

• pip install -e . (or just setting PYTHONPATH to point at mypy) includes commit hash
• python setup.py bdist_wheel does not include commit hash

We want to keep the above unchanged.

We want this to happen:

• pip install /local/repo, and pip install git+git://github.com/python/mypy.git should also include commit hash
• building the wheel should complain if version hard coded in version.py doesn't match the HEAD commit tag

Correct?