single table DELETE...SELECT clauses when innobase_locks_unsafe_for_binlog
is used and isolation level of the transaction is not serializable. 
InnoDB uses consistent read in these cases for a selected table.
Backported from 5.0.x.


sql/ha_innodb.cc:
  Relaxed locking in INSERT...SELECT, single table UPDATE...SELECT and 
  single table DELETE...SELECT clauses when innobase_locks_unsafe_for_binlog
  is used and isolation level of the transaction is not serializable. 
  InnoDB uses consistent read in these cases for a selected table.