fix(git): abort cherry-pick on failure

[sentry]

Fixes WEBLATE-37ZV.

The issue was that: Cherry-pick fails due to merge conflicts, and the custom merge driver's immediate exit on WEBLATE_MERGE_SKIP causes RepositoryError to be raised.

This pull request addresses the issue by:

• Adding a try-except block around the git cherry-pick command.
• If cherry-pick fails, git cherry-pick --abort is executed to clean up the repository state.
• The original RepositoryError is then re-raised.

This fix was generated by Seer in Sentry, triggered by Michal Čihař. 👁️ Run ID: 857074

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[sentry]

Bug: The error handler for a failed git cherry-pick unconditionally calls cherry-pick --abort, which can fail and mask the original error if no cherry-pick was in progress.
_{Severity: MEDIUM}

Suggested Fix

Before calling repository.execute(["cherry-pick", "--abort"]), check if a cherry-pick operation is actually in progress. This can be done by verifying the existence of the .git/CHERRY_PICK_HEAD file, for example: if repository.has_git_file("CHERRY_PICK_HEAD"): repository.execute(["cherry-pick", "--abort"]). This aligns with the established defensive pattern used for rebase and merge aborts in the codebase.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: weblate/addons/git.py#L221-L223

Potential issue: The new error handling in the `squash_author` method calls
`repository.execute(["cherry-pick", "--abort"])` within an `except RepositoryError`
block. However, if the initial `cherry-pick` fails for reasons that do not leave the
repository in a cherry-pick state (e.g., an invalid commit reference), the `cherry-pick
--abort` command will also fail. This second failure raises a new `RepositoryError`,
masking the original, more informative error. This behavior is inconsistent with
existing patterns for `rebase --abort` and `merge --abort` in the codebase, which check
the repository state before attempting to abort. The same issue exists in a second
`cherry-pick` operation in the same method.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[nijel]

Superseeded by #18337

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.98%. Comparing base (7e5b583) to head (239f46d).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
weblate/addons/git.py	40.00%	3 Missing ⚠️

❌ Your patch status has failed because the patch coverage (40.00%) is below the target coverage (100.00%). You can increase the patch coverage or adjust the target coverage.

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