We're running a multi-master setup between 2 machines where they are both a master and a slave of the other master.
When we upgraded one of the servers from 5.5.27 to 5.5.28 the binlogs were all removed which broke the replication. The file and position had to be reset its slave.
We thought this was an unlucky anomaly, but when we upgraded the other server the same thing happened again.
I couldn't find anything in the Changelog for this version so this is probably a bug then?