in tests after the last 4.1->5.0 merge, and:
*** The same as ChangeSet@1.1822.1.1, 2004-05-14 23:08:03+02:00, guilhem@mysql.com of MySQL 4.0 ***
  Replication testsuite: making the master-slave synchronization less likely to fail,
  by adding sleep-and-retries (max 4 times) if MASTER_POS_WAIT() returns NULL
  in sync_with_master and sync_slave_with_master.
  The problem showed up only today, in MySQL 5.0 in rpl_server_id2.test,
  but may affect 4.x as well, so I fixed 4.x too. Note that I am also fixing
  5.0, with the same exact patch, because I don't want to leave 5.0 broken
  until the next 4.0->4.1->5.0 merge.