2019-01-25 22:27:52,536 ERROR zuul.MergeServer: Exception while running job
Traceback (most recent call last):
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/zuul/merger/server.py", line 89, in run
    self.merge(job)
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/zuul/merger/server.py", line 104, in merge
    commit = self.merger.mergeChanges(args['items'])
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/zuul/merger/merger.py", line 363, in mergeChanges
    commit = self._mergeItem(item, recent)
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/zuul/merger/merger.py", line 310, in _mergeItem
    commit = repo.getCommitFromRef(zuul_ref)
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/zuul/merger/merger.py", line 138, in getCommitFromRef
    if refname not in repo.refs:
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/git/repo/base.py", line 248, in references
    return Reference.list_items(self)
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/git/util.py", line 745, in list_items
    out_list.extend(cls.iter_items(repo, *args, **kwargs))
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/git/refs/symbolic.py", line 594, in _iter_items
    for sha, rela_path in cls._iter_packed_refs(repo):
  File "/usr/share/python/zuul/local/lib/python2.7/site-packages/git/refs/symbolic.py", line 98, in _iter_packed_refs
    raise TypeError("PackingType of packed-Refs not understood: %r" % line)
TypeError: PackingType of packed-Refs not understood: '# pack-refs with: peeled fully-peeled sorted'