fix: streamline repo cloning logic in gitutil.go

[idsulik]

Fixes: #9878

Description
Fixed error handling to properly fall back from branch-based cloning to commit SHA fetching when needed.
Previously, the code parsed error messages to determine fallback behavior, which is fragile and can break if git changes its error messages

[gemini-code-assist]

Summary of Changes

Hello @idsulik, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refines the Git repository cloning process within gitutil.go to enhance robustness and error handling. It ensures that if a direct shallow clone targeting a specific branch or reference encounters an issue, the system gracefully falls back to a more comprehensive cloning strategy, improving the reliability of repository synchronization.

Highlights

• Improved Git Cloning Fallback: The logic for cloning a Git repository has been streamlined. If an initial shallow clone attempt with a specific branch fails, the system now directly attempts a full clone of the repository, followed by a checkout of the desired reference.
• Simplified Error Handling: The explicit check for 'Could not find remote branch' error message has been removed, making the fallback mechanism more robust to various initial cloning failures.
• Full Clone on Fallback: The fallback cloning operation no longer uses the '--depth 1' flag, ensuring a full repository clone when the initial shallow clone fails.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request streamlines the git cloning logic by removing a brittle check on an error message. The new approach correctly falls back to a full clone when a shallow clone by branch fails, which is a good improvement for robustness when dealing with commit SHAs. I've added one comment to further improve the reliability of the fallback logic by ensuring a clean state before retrying the clone operation.