This is imported from bugzilla item: http://bugs.mariadb.com/show_bug.cgi?id=663
Monitor logic is invalid when it attempts to find out who was the last known master.
Reproduce by starting MaxScale so that master is not responsive. While monitor tries to find the master fail one of the slaves. After a while monitor starts to log invalid information about backend roles:
2014-12-29 16:16:09 Error : No Master can be determined. Last known was 127.0.0.1:3001
2014-12-29 16:16:29 Error : No Master can be determined. Last known was 127.0.0.1:3001