There is something wrong with the gtest repository

trond@ok-2:1022> repo init -u git://github.com/couchbase/manifest -m branch-master.xml
[ ... cut ... ]
trond@ok-2:1023> repo sync
[ ... cut ... ]
trond@ok-2:1024> repo start foo --all && repo prune
Traceback (most recent call last):
File "/Users/trond/compile/couchbase/trunk/.repo/repo/main.py", line 506, in <
_Main(sys.argv[1:])
File "/Users/trond/compile/couchbase/trunk/.repo/repo/main.py", line 482, in _
result = repo._Run(argv) or 0
File "/Users/trond/compile/couchbase/trunk/.repo/repo/main.py", line 161, in _
result = cmd.Execute(copts, cargs)
File "/Users/trond/compile/couchbase/trunk/.repo/repo/subcmds/prune.py", line
all_branches.extend(project.PruneHeads())
File "/Users/trond/compile/couchbase/trunk/.repo/repo/project.py", line 1529,
self.bare_git.DetachHead(rev)
File "/Users/trond/compile/couchbase/trunk/.repo/repo/project.py", line 2460,
self.update_ref(*cmdv)
File "/Users/trond/compile/couchbase/trunk/.repo/repo/project.py", line 2551,
p.stderr))
error.GitError: gtest update-ref: error: Trying to write non-commit object 89264
fatal: update_ref failed for ref 'HEAD': Cannot update the ref 'HEAD'.