Transaction on the slave sql thread got blocked against a slave's mysqld local ta's
lock. Since the default, slave-transaction-retries=10, there was replaying of the 
replicated ta. That failed because of a new started from 5.0.13 policy not to rollback
a timed-out transaction. Effectively the first round of a timed-out ta becomes committed
by the replaying's first "BEGIN".

It was decided to backport already existed method working in 5.1 implemented in
bug #16228 for handling symmetrical deadlock problem. That patch introduced end_trans
execution whenever a replicated ta deadlocks or timed-out.

Note, that this solution can be practically suboptimal - in the light of the changed behavior
due to timeout we still could replay only the last statement -  only with a high rate of timeouting
replicated transactions.