BUG#29046: rpl_stm_mystery22 unstable

Problem: rpl_stm_mystery22 is unstable.

Reason: At one place, the test case *should* wait until the SQL thread on the
slave receives an error, but instead it waits until the SQL thread stops. The
SQL thread may stop before the error flag is set, so that when the test case
continues to execute, the error flag is not set.

Fix: Introduce the subroutine mysql-test/include/wait_for_slave_sql_error.inc,
which waits until there is an error in the sql thread of the slave.

Re-commit: fixed one logical error and two smaller things noted by Mats.

mysql-test/include/wait_for_slave_sql_error.inc

+###################################################
+#Author: Sven
+#Date: 2007-10-09
+#Purpose: Wait until the slave has an error in the
+#         sql thread, as indicated by
+#         "SHOW SLAVE STATUS", or at most 30
+#         seconds.
+#Details:
+#      1) Fill in and setup variables
+#      2) loop, looking for sql error on slave
+#      3) If it loops too long, die.
+####################################################
+connection slave;
+let $row_number= 1;
+let $run= 1;
+let $counter= 300;
+
+while ($run)
+{
+  let $sql_result= query_get_value("SHOW SLAVE STATUS", Last_SQL_Errno, $row_number);
+  let $run= `SELECT '$sql_result' = '0'`;
+  if ($run) {
+    real_sleep 0.1;
+    if (!$counter){
+      --echo "Failed while waiting for slave to produce an error in its sql thread"
+      --replace_result $MASTER_MYPORT MASTER_PORT
+      --replace_column 1 # 7 # 8 # 9 # 22 # 23 # 33 #
+      query_vertical SHOW SLAVE STATUS;
+      exit;
+    }
+    dec $counter;
+  }
+}

mysql-test/suite/rpl/t/rpl_stm_mystery22.test

@@ -28,7 +28,7 @@ insert into t1 values(NULL,'new');
 save_master_pos;
 connection slave;
 # wait until the slave tries to run the query, fails and aborts slave thread
-wait_for_slave_to_stop;
+source include/wait_for_slave_sql_error.inc;
 select * from t1 order by n;
 delete from t1 where n = 2;
 --disable_warnings