Determine the current revision identifier for the working directory
        of this Repository

        Returns:
            str: git HEAD revision identifier
                (``git rev-parse --short HEAD``)

def current_id(self):
        """
        Determine the current revision identifier for the working directory
        of this Repository

        Returns:
            str: git HEAD revision identifier
                (``git rev-parse --short HEAD``)
        """
        try:
            cmd = ['git', 'rev-parse', '--short', 'HEAD']
            return self.sh(cmd,
                        shell=False,
                        ignore_error=True).rstrip()
        except subprocess.CalledProcessError as e:
            log.exception(e)
            #if e.returncode == 128  # bare repo
            return None