The updating of GTIDs was only considered successful if both the current
GTID position and binlog GTID positions were non-empty. If a slave has no
binlogged events, the GTID update would always fail.
This change in behavior caused the mysqlmon_failover_auto and
mysqlmon_failver_manual tests to break. The test disabled the binary log
on one of the servers which caused it to be left out from the rejoining
process.