Function git_failure_detail 

pub fn git_failure_detail(
    stderr: &[u8],
    stdout: &[u8],
    status: ExitStatus,
) -> String

Build a human-readable failure detail from a git subprocess’s captured output. Prefers stderr (where git writes diagnostics), falls back to stdout (some errors — e.g. a git add index lock — print there), then to the exit status when both are empty. Control and ANSI escape bytes are stripped so a hostile remote’s error text can’t manipulate the terminal (#307), and the result is credential-scrubbed via sanitize_git_url so a URL with embedded credentials never echoes the secret to the terminal or logs (#312).