Return the number of commits we are relative to the remote. Negative
        is behind, positive in front, zero means we are matched to remote.

def get_relative_to_remote(self):
        """Return the number of commits we are relative to the remote. Negative
        is behind, positive in front, zero means we are matched to remote.
        """
        s = self.git("status", "--short", "-b")[0]
        r = re.compile("\[([^\]]+)\]")
        toks = r.findall(s)
        if toks:
            try:
                s2 = toks[-1]
                adj, n = s2.split()
                assert(adj in ("ahead", "behind"))
                n = int(n)
                return -n if adj == "behind" else n
            except Exception as e:
                raise ReleaseVCSError(
                    ("Problem parsing first line of result of 'git status "
                     "--short -b' (%s):\n%s") % (s, str(e)))
        else:
            return 0