Function getCommonDir

src/utils/git/gitFilesystem.ts:273–280

(gitDir: string)

 * Returns null if no commondir file exists (regular repo).
 */
export async function getCommonDir(gitDir: string): Promise<string | null> {
  try {
    const content = (await readFile(join(gitDir, 'commondir'), 'utf-8')).trim()
    return resolve(gitDir, content)
  } catch {
    return null
  }
}

/**
 * Read a raw symref file and extract the branch name after a known prefix.