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

sql/event_data_objects.cc

@@ -1473,20 +1473,23 @@ end:
       thd->tx_read_only= false;
 
 #ifdef WITH_WSREP
-      // 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;
-      WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL);
+      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 *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);
 
-#ifdef WITH_WSREP      
+#ifdef WITH_WSREP
       WSREP_TO_ISOLATION_END;
   error:
-#endif      
+#endif
       thd->tx_read_only= save_tx_read_only;
       thd->security_ctx->master_access= saved_master_access;
     }