pip freeze figures out the current commit SHA for a git repo but not (reliably) the current branch

[bjonen]

The problem originates from this line.

names_by_commit = dict((commit, ref) for ref, commit in refs.items())

When local branches track up to date remote branches, the mapping from SHA to branch is not unique and remote branches with syntax "origin/my_branch" may be picked (see comment in the code), even though they are NOT checked out.
Finally, pkg_resources does not allow a slash in the version pattern and raises a ValueError if a branch name containing a slash is picked.

My use case:
I have a local git repo which originates from a different local path on my file system. I installed it via:

pip install -e c:/workspace/my_proj

Now I do

pip freeze > requirements.txt

The file looks something like this:

-e git+<path_to_origin>/my_proj.git@<SHA>#egg=my_proj-origin/<branch>

If I then create a new virtual environment and try to install my requirements file I get an error in pip_vendor\pkg_resources.py", line 2573, in scan_list.

ValueError: ('Expected version spec in', 'my_proj-origin/<branch>', 'at', '/<branch>')

I noticed that the problem goes away when the line in the requirements file reads:

-e git+<path_to_origin>/my_proj.git@<SHA>#egg=my_proj-<branch>

[bjonen]

Following the command proposed here:

git rev-parse --abbrev-ref HEAD

It would be easy to add a method similar to get_revision to git.py

def get_branch:
    current_branch = call_subprocess(
            [self.cmd, 'rev-parse',--abrev-ref, 'HEAD'], show_stdout=False, cwd=location)
        return current_branch.strip()

Then there would be no need for randomly picking a branch, which the user might or might not be currently on. If you want I can prepare a PR for this.

[cjerdonek]

The non-determinism has been reported here: #1867

Similarly, the issue with the slash has been reported here: #1083

[bjonen]

@cjerdonek Thanks for the links!

I don't think #1867 goes far enough though. I think it makes more sense to "freeze" the current branch instead of some pointer to the current commit, even if this pointer is made deterministic through msabramo@7473615.

[dstufft]

Looking at this, this appears to still be a real issue, however I believe the correct behavior here is to pin it to a commit and not keep a branch at all. Freezing an environment is intended to reproduce the current environment.

[sbidoul]

The branch is not emitted by pip freeze anymore since #3312, only the commit id. So we'll let the bot close this unless there is a reaction otherwise.

[no-response]

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.