The problem is that since MyISAM's concurrent_insert is on by
default some concurrent SELECT statements might not see changes
made by INSERT statements in other connections, even if the
INSERT statement has returned.

The solution is to disable concurrent_insert so that INSERT
statements returns after the data is actually visible to other
statements.

different error code depending on platform.

On Mac OS X, KILL statement issued to kill the current
connection would return a different error code and message than on
other platforms ('MySQL server has gone away' instead of 'Shutdown
in progress').

The reason for this difference was that on Mac OS X we have macro
SIGNAL_WITH_VIO_CLOSE defined. This macro forces KILL
implementation to close the communication socket of the thread
that is being killed. SIGNAL_WITH_VIO_CLOSE macro is defined on
platforms where just sending a signal is not a reliable mechanism
to interrupt the thread from sleeping on a blocking system call.
In a nutshell, closing the socket is a hack to work around an
operating system bug and awake the blocked thread no matter what.

However, if the thread that is being killed is the same
thread that issued KILL statement, closing the socket leads to a
prematurely lost connection. At the same time it is not necessary
to close the socket in this case, since the thread in question
is not inside a blocking system call.

The fix, therefore, is to not close the socket if the thread that
is being killed is the same that issued KILL statement, even with
defined SIGNAL_WITH_VIO_CLOSE.

The reason the "reap;" succeeds unexpectedly is because the query was completing(almost always) and the network buffer was big enough to store the query result (sometimes) on Windows, meaning the response was completely sent before the server thread could be killed.

Therefore we use a much longer running query that doesn't have a chance to fully complete before the reap happens, testing the kill properly.

mysqld crashed when a long-running explain query was killed from
another connection.

When the current thread caught a kill signal executing the function
best_extension_by_limited_search it just silently returned to  
the calling function greedy_search without initializing elements of
the join->best_positions array.
However, the greedy_search function ignored thd->killed status
after a calls to the best_extension_by_limited_search function, and
after several calls the greedy_search function used an uninitialized
data from the join->best_positions[idx] to search position in the
join->best_ref array. 
That search failed, and greedy_search tried to call swap_variables
function with NULL argument - that caused a crash.

If a stored function or a trigger was killed it had aborted but no error
was thrown. This allows the caller statement to continue without a notice.
This may lead to a wrong data being inserted/updated to/deleted as in such
cases the correct result of a stored function isn't guaranteed. In the case
of triggers it allows the caller statement to ignore kill signal and to
waste time because of re-evaluation of triggers that always will fail
because thd->killed flag is still on.

Now the Item_func_sp::execute() and the sp_head::execute_trigger() functions
check whether a function or a trigger were killed during execution and
throws an appropriate error if so.
Now the fill_record() function stops filling record if an error was reported
through thd->net.report_error.

Events: crash with procedure which alters events with function

Post-review CS

This fix also changes the handling of KILL command combined with
subquery. It changes the error message given back to "not supported",
from parse error. The error for CREATE|ALTER EVENT has also been changed
to generate "not supported yet" instead of parse error.
In case of a SP call, the error is "not supported yet". This change
cleans the parser from code which should not belong to there. Still
LEX::expr_allows_subselect is existant because it simplifies the handling
 of SQLCOM_HA_READ which forbids subselects.

Update tests and result files after running with new mysqltest that better detects problems with test files

 - ie. backport from 5.1
 - also update testcase error dected by new version

- Fixed tests
- Optimized new code
- Fixed some unlikely core dumps
- Better bug fixes for:
  - #14397 - OPTIMIZE TABLE with an open HANDLER causes a crash
  - #14850 (ERROR 1062 when a quering a view using a Group By on a column that can be null

--disable_reconnect and --enable_reconnect to mysqltest
so that it can be tested properly. (Bug #8866)

been killed.

    added support for quiet
    increased line buffer size
client/mysqltest.c
    fixed memory leak
    added query logging to result file
    added error message logging to result file
    added enable_query_log/disable_query_log
mysql-test/mysql-test-run.sh
    converted tests to use mysqlmanager

Updated test results

added support for kill expr
fixed coredump in set @A := foo;
added testcase for user_var
added testcase for kill