ha_innodb.cc:

  Fix part of bug #9670: if MySQL calls ::store_lock with TL_IGNORE, do not change prebuilt->select_lock_type; this fix may heal the assertion failures reported in UPDATE and multi-table UPDATE; it is not clear if this fixes the problems in OPTIMIZE TABLE

sql/ha_innodb.cc

@@ -5320,7 +5320,8 @@ ha_innobase::store_lock(
 	    (lock_type == TL_READ_HIGH_PRIORITY && thd->in_lock_tables) ||
 	    lock_type == TL_READ_WITH_SHARED_LOCKS ||
 	    lock_type == TL_READ_NO_INSERT ||
-	    thd->lex->sql_command != SQLCOM_SELECT) {
+	    (thd->lex->sql_command != SQLCOM_SELECT
+	     && lock_type != TL_IGNORE)) {
 
 		/* The OR cases above are in this order:
 		1) MySQL is doing LOCK TABLES ... READ LOCAL, or