If the SQL Thread fails to execute an event due to a temporary error (e.g.
ER_LOCK_DEADLOCK) and the option "--slave_transaction_retries" is set the SQL
Thread should not be aborted and the transaction should be restarted from the
beginning and re-executed.

Unfortunately, a wrong interpretation of the THD::is_fatal_error was preventing
this behavior. In a nutshell, "this variable is set to TRUE if an execution of a
compound statement cannot continue. In particular, it is used to disable access
to the CONTINUE or EXIT handlers of stored routines. So even temporary errors
may have this variable set.

To fix the bug, we have done what follows:

   DBUG_ENTER("has_temporary_error");

-  if (thd->is_fatal_error)
-    DBUG_RETURN(0);
-
   DBUG_EXECUTE_IF("all_errors_are_temporary_errors",
                   if (thd->main_da.is_error())
                   {