Function open_loops 

pub fn open_loops(
    repo: &Path,
    root_label: &str,
    need_ahead_behind: bool,
) -> Result<Vec<OpenLoop>>

Returns all unmerged branches (except default) in a repo.

Light phase (default branch, merged set, for-each-ref) always runs. The heavy phase (rev-list for ahead/behind) runs only when need_ahead_behind is true.

Errors

Returns Err if git fails or if the default branch is not found.