NULL _self value after (many) reconfigurations, when the reconfiguration data actually does contain the server host/port doing the reconfiguration. Can be tracked by a NULL _self value in ReplSetImpl::syncThread after running many tests from jstests/repl/priority1.js.

Bandaged the problem so far by disabling the sync when self is not detected after the reconfigure. See https://github.com/mongodb/mongo/commit/a4467c4849e2032f682598e06ba5437e843d1125