Follow-up patch for lp:1312618 to fix a segfault.

sql/event_data_objects.cc

@@ -1473,12 +1473,15 @@ end:
       thd->tx_read_only= false;
 
 #ifdef WITH_WSREP
+      if (WSREP(thd)) {
         // sql_print_information("sizeof(LEX) = %d", sizeof(struct LEX));
         // sizeof(LEX) = 4512, so it's relatively safe to allocate it on stack.
-      LEX lex;
-      lex.sql_command = SQLCOM_DROP_EVENT;
-      thd->lex = &lex;
+        LEX *old_lex= thd->lex, new_lex;
+        new_lex.sql_command= SQLCOM_DROP_EVENT;
+        thd->lex= &new_lex;
         WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);
+        thd->lex= old_lex;
+      }
 #endif
 
       ret= Events::drop_event(thd, dbname, name, FALSE);