Merge with MySQL 5.1.55

- Fixed some issues with partitions and connection_string, which also fixed lp:716890 "Pre- and post-recovery crash in Aria"
- Fixed wrong assert in Aria

Now need to merge with latest xtradb before pushing 

sql/ha_partition.cc:
  Ensure that m_ordered_rec_buffer is not freed before close.
sql/mysqld.cc:
  Changed to use opt_stack_trace instead of opt_pstack.
  Removed references to pstack
sql/partition_element.h:
  Ensure that connect_string is initialized
storage/maria/ma_key_recover.c:
  Fixed wrong assert

mysql-test/suite/rpl/t/rpl_rotate_logs.test

@@ -18,19 +18,14 @@
 -- source include/have_binlog_format_mixed_or_statement.inc
 
 connect (master,localhost,root,,test,$MASTER_MYPORT,$MASTER_MYSOCK);
---disable_warnings
-drop table if exists t1, t2, t3, t4;
---enable_warnings
 connect (slave,localhost,root,,test,$SLAVE_MYPORT,$SLAVE_MYSOCK);
+
 # Create empty file
 let $MYSQLD_SLAVE_DATADIR= `select @@datadir`;
 write_file $MYSQLD_SLAVE_DATADIR/master.info;
 EOF
 chmod 0000 $MYSQLD_SLAVE_DATADIR/master.info;
 connection slave;
---disable_warnings
-drop table if exists t1, t2, t3, t4;
---enable_warnings
 
 # START SLAVE will fail because it can't read the file (mode 000)
 # (system error 13)
@@ -97,11 +92,9 @@ connection master;
 set insert_id=1234;
 insert into t2 values(NULL);
 connection slave;
---source include/wait_for_slave_sql_to_stop.inc
-
-#restart slave skipping one event
-set global sql_slave_skip_counter=1;
-start slave;
+# 1062 = ER_DUP_ENTRY
+--let $slave_sql_errno= 1062
+--source include/wait_for_slave_sql_error_and_skip.inc
 
 connection master;
 
@@ -194,3 +187,5 @@ show binlog events in '';
 purge master logs before now();
 
 --echo End of 5.0 tests
+--source include/stop_slave.inc
+CHANGE MASTER TO MASTER_HOST = '';