Pierre-Yves David <pierre-yves.david@fb.com> [Thu, 19 Mar 2015 13:00:44 -0700] rev 24393
obsolete: avoid infinite loop from obs-cycle in divergence (issue4126)
As for other currently in place cycle detection, arbitrarily cut the first
obsolescence link that create a cycle avoiding the infinite loop. This will have
to be made more deterministic in the future but we do not really care right now.