Fix 100725: Allow empty repositories to be synced

[plainerman]

This PR fixes #100725 and allows VSCode to properly sync git repositories that have been cloned before there were any commits.

Reproducing and Testing

To test it, I have attached a zip file with an empty git repository that now has commits (i.e. should be syncable).

1. Download and unpack this repository empty.zip.
   If you feel uncomfortable downloading files from strangers, see below for git commands to simulate this state.
2. Open the folder in VSCode.
3. With the current version of VSCode (as seen in the gif in the issue Git - git sync issue on an empty repo #100725 (comment)), the git repository cannot be synced. Manually executing the command git pull works just fine.
   With the proposed fix, clicking the sync button works and syncs the repository as intended.

Proposed Changes

As described in the issue (#100725), the root cause is that the command used to fetch the upstream (git rev-parse) fails on an empty repository. This then causes this unexpected behavior.

I propose the following changes to resolve the issue:

extensions/git/src/git.ts method: getBranch(...)

1. Wrap fetching the latest commit in a try-catch
   Although the commit cannot be fetched for an empty repository, without this catch the function is exited. The commit should be left undefined, while still properly fetching the upstream.
2. Fetch the upstream via the git.config
   Once a branch has an upstream, it will be stored in the git config. Unfortunately, this command uses an older syntax of git, so we have to manually construct the full upstream path. See this stackoverflow post for more information about this section of the git config.

extensions/git/src/statusbar.ts method: command()
3. Do not require commit for syncing
Syncing a repository does not require a commit, whereas publishing does (git does not allow pushing branches without a history).
In combination with the proposed changes above, this makes the sync button clickable.

You might feel uncomfortable changing from git-rev to git-config in all cases. Although I strongly believe that this should not be a problem and did not cause any issues whatsoever in my tests: If you feel so, I am open for discussion. In the worst case, I can revert the last commit and we use git-config as a fallback. This can be seen in this commit: 4f3d47c
Personally, I would prefer the current changes.

Simulate a freshly cloned empty git repo

mkdir empty
cd empty
git init

# Add some origin, you can use any repo, but this is very small
git remote add origin https://github.com/plainerman/empty.git

# Now track master as described in here https://stackoverflow.com/a/625460/4417954
git config branch.master.remote origin
git config branch.master.merge refs/heads/master

[eamodio]

I'm definitely hesitant to change the default behavior, but I think its probably a decent fallback. I've started a discussion for this here: git-for-windows/git#2981 to see what any Git maintainers might think.

[plainerman]

@eamodio, with the answer from @derrickstolee in git-for-windows/git#2981 should I revert the last commit and add git-config as fallback?
Or would you like to wait for other responses / further evaluation?

[eamodio]

Yeah I think we should add it as a fallback.

[plainerman]

I have reverted the commit and git-config is the fallback behavior now.

Somehow, the windows tests are now failing. I believe that this is not related to my changes (other PRs are also failing). Maybe you could take a quick look at it.

Are there any other changes I should include? Or is this PR good to go (once the pipeline succeeds)?

[plainerman]

I am looking forward to merging this PR. @eamodio, have you already had the time to look at my questions?
Thank you very much.

[plainerman]

@eamodio I hope you are doing well.
I have just resolved the merge conflicts that came up. From my side, the PR is now ready again and I am looking froward to your review. Any updates?

[plainerman]

@eamodio
I was wondering whether we could assign this to the February Milestone?
Thank you

[plainerman]

@joaomoreno, I haven't heard from @eamodio in a while (probably he is busy).
Since you were also involved in the issue, I was wondering whether we could discuss this implementation or if you know anything about @eamodio?

[plainerman]

@joaomoreno, @eamodio I hope you are doing well.
I haven't heard back from you in quite some time now. I would love to get a code review and eventually merge this PR.
Is there anything I can do to help? Or can you give me an estimate on when you will have time?

Thank you very much

[joaomoreno]

@plainerman I understand how frustrating it might be to just see your work pending here. But I have to ask for patience. We have no estimate right now. We're just busy with many other tasks right now. @eamodio will look into this when he carves out the time. Thanks!

[eamodio]

@plainerman sorry for the delay. Can you please update this with the current main branch?

Also can you combine the extra git calls into a single call? Here is what I have in GitLens: https://github.com/eamodio/vscode-gitlens/blob/b60637f00e245fd23c84ceebf7a4aeb637c64d96/src/git/git.ts#L1255-L1274

[plainerman]

Thank you for your responses!

I will incorporate the desired changes and will ping you @eamodio once I have changed this.

[plainerman]

Sorry @eamodio, I was busy the last days. The branch is now ready again.

I rebased the branch and combined the git config fetch into a single call. If there is anything I can do, just ping me.

To test it locally, you can use this empty repository. that has a commit but is not synced.

[plainerman]

@lszomoru, I am glad to help if you need any assistance or have further questions.

[lszomoru]

@plainerman, first of all I would like to apologise that it is taking so long for this change to be committed. I have taken a look at your code today, and I have manually ported the two changes to the latest codebase in main. Unfortunately I am still seeing errors when I do the following:

mkdir empty
cd empty
git init

# Add some origin, you can use any repo, but this is very small
git remote add origin https://github.com/plainerman/empty.git

# Now track master as described in here https://stackoverflow.com/a/625460/4417954
git config branch.master.remote origin
git config branch.master.merge refs/heads/master

When I open the repository, with your changes the Sync button is currently enabled in the status bar, but when I click on it I am getting the following error message in the Git output: fatal: couldn't find remote ref master. The same error happens if I push a commit and attempt to sync after the commit has been pushed.

I will further investigate the issue this week but please feel free to look at it yourself If you have time.

[plainerman]

Thanks @lszomoru for the update. Maybe, I'll have time this weekend. Have you pushed the changes you made to my repository? I believe you have push permissions there, as you are a member here. Or should I rebase myself?

[lszomoru]

@plainerman, no I have not pushed any changes to your topic branch.
I have manually ported the two changes from this pull request onto main and tested things.

[vivodi]

Is this still relevant?