When looking up the error number for named errors in mysqltest .test
  files, we inadvertantly would match ER_WRONG_VALUE against
  ER_WRONG_VALUE_COUNT because we were using the length of the shorter
  string in strncmp(). Now we double-check the length of matches to
  make sure it was a complete match.


client/mysqltest.c:
  Check the length of the error name to make sure it wasn't just a
  partial match
mysql-test/t/events.test:
  Replace error numbers with error names, with side-effect of testing
  Bug #18495.