This is MySQL Bug#59123. The message string stored in an INCIDENT event was
not zero-terminated. This caused any following checksum bytes (if enabled on
the master) to be output to the error log as trailing garbage when the message
was printed to the error log.

Backport the patch from MySQL 5.6:

  revno: 2876.228.200
  revision-id: zhenxing.he@sun.com-20110111051323-w2xnzvcjn46x6h6u
  committer: He Zhenxing <zhenxing.he@sun.com>
  timestamp: Tue 2011-01-11 13:13:23 +0800
  message:
    BUG#59123 rpl_stm_binlog_max_cache_size fails sporadically with found warnings

Also add a test case.