Make mysqlbinlog omit redundant `use` around BEGIN/SAVEPOINT/COMMIT/ROLLBACK in 5.0 binlogs

This is a merge of percona patch mysqlbinlog_fix.patch.

Apparently, MySQL 5.0 does not flag BEGIN/SAVEPOINT/COMMIT/ROLLBACK statements
in its binlogs with LOG_EVENT_SUPPRESS_USE_F like 5.1+ does. This causes
unnecessary `use` statements around such statements when the binlog is dumped
by mysqlbinlog.

Fix by always suppressing the output of `use` for these statements.

client/mysqlbinlog.cc

@@ -842,8 +842,19 @@ Exit_status process_event(PRINT_EVENT_INFO *print_event_info, Log_event *ev,
     case QUERY_EVENT:
     {
       Query_log_event *qe= (Query_log_event*)ev;
-      if (!qe->is_trans_keyword() && shall_skip_database(qe->db))
-        goto end;
+      if (!qe->is_trans_keyword())
+      {
+        if (shall_skip_database(qe->db))
+          goto end;
+      }
+      else
+      {
+        /*
+          In case the event for one of these statements is obtained
+          from binary log 5.0, make it compatible with 5.1
+        */
+        qe->flags|= LOG_EVENT_SUPPRESS_USE_F;
+      }
       print_use_stmt(print_event_info, qe->db, qe->db_len);
       if (opt_base64_output_mode == BASE64_OUTPUT_ALWAYS)
       {

mysql-test/r/mysqlbinlog.result

@@ -222,7 +222,6 @@ ROLLBACK /* added by mysqlbinlog */;
 /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
 DELIMITER /*!*/;
 ROLLBACK/*!*/;
-use test/*!*/;
 SET TIMESTAMP=1108844556/*!*/;
 SET @@session.pseudo_thread_id=999999999/*!*/;
 SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
@@ -230,6 +229,7 @@ SET @@session.lc_time_names=0/*!*/;
 SET @@session.collation_database=DEFAULT/*!*/;
 BEGIN
 /*!*/;
+use test/*!*/;
 SET TIMESTAMP=1108844555/*!*/;
 insert t1 values (1)
 /*!*/;
@@ -241,7 +241,6 @@ Warning: The option '--position' is deprecated and will be removed in a future r
 /*!40019 SET @@session.max_insert_delayed_threads=0*/;
 /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
 DELIMITER /*!*/;
-use test/*!*/;
 SET TIMESTAMP=1108844556/*!*/;
 SET @@session.pseudo_thread_id=999999999/*!*/;
 SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
@@ -249,6 +248,7 @@ SET @@session.lc_time_names=0/*!*/;
 SET @@session.collation_database=DEFAULT/*!*/;
 BEGIN
 /*!*/;
+use test/*!*/;
 SET TIMESTAMP=1108844555/*!*/;
 insert t1 values (1)
 /*!*/;
@@ -584,7 +584,6 @@ SET @@session.lc_time_names=0/*!*/;
 SET @@session.collation_database=DEFAULT/*!*/;
 BEGIN
 /*!*/;
-use test/*!*/;
 SET TIMESTAMP=1266652094/*!*/;
 SavePoint mixed_cases
 /*!*/;
@@ -595,11 +594,9 @@ INSERT INTO db1.t2 VALUES("in savepoint mixed_cases")
 SET TIMESTAMP=1266652094/*!*/;
 INSERT INTO db1.t1 VALUES(40)
 /*!*/;
-use test/*!*/;
 SET TIMESTAMP=1266652094/*!*/;
 ROLLBACK TO mixed_cases
 /*!*/;
-use db1/*!*/;
 SET TIMESTAMP=1266652094/*!*/;
 INSERT INTO db1.t2 VALUES("after rollback to")
 /*!*/;
@@ -627,7 +624,6 @@ SET @@session.lc_time_names=0/*!*/;
 SET @@session.collation_database=DEFAULT/*!*/;
 BEGIN
 /*!*/;
-use test/*!*/;
 SET TIMESTAMP=1266652094/*!*/;
 SavePoint mixed_cases
 /*!*/;