Backport of Bug#47304 to mysql-next-mr

------------------------------------------------------------
revno: 3624
revision-id: jon.hauglid@sun.com-20090928163426-2lg1gofzz44xzzxf
parent: alik@sun.com-20090928050057-r0a62x9czr01q7oe
committer: Jon Olav Hauglid <jon.hauglid@sun.com>
branch nick: mysql-6.0-codebase-bugfixing-bug47304
timestamp: Mon 2009-09-28 18:34:26 +0200
message:
  Bug #47304 Test main.mdl_sync fails on embedded server

  The problem was that SHOW PROCESSLIST was trying to access
  a thread that was not properly running and therefore had an 
  uninitialized mutex.

  This patch explicitly resets thd->mysys_var after each embedded
  server command to prevent the mutex from being accessed in an
  illegal state.

  The patch also re-enables lock_multi.test and mdl_sync.test for 
  embedded server as they had been disabled because of this bug.

libmysqld/lib_sql.cc

@@ -138,6 +138,7 @@ emb_advanced_command(MYSQL *mysql, enum enum_server_command command,
 
   result= dispatch_command(command, thd, (char *) arg, arg_length);
   thd->cur_data= 0;
+  thd->mysys_var= NULL;
 
   if (!skip_check)
     result= thd->is_error() ? -1 : 0;

mysql-test/t/lock_multi.test

--- source include/not_embedded.inc
-
 # Save the initial number of concurrent sessions
 --source include/count_sessions.inc