mysql_upgrade was passing an non-initialized non-null tmpdir to create_temp_file() if no 
--tmpdir was specified. This prevents create_temp_file() from taking the system 
temporary file path and as a result mysql_upgrade was trying to open a file in a 
directory that it may not have write access to.
Fixed by making sure mysql_upgrade will pass a zero length temp dir string to 
create_temp_file() if no --tmpdir is specified.

output from HANDLER ... READ .. NEXT ...

Spatial indexes were not checking for out-of-record condition in
the handler next command when the previous command didn't found
rows.

Fixed by making the rtree index to check for end of rows condition
before re-using the key from the previous search.

Fixed another crash if the tree has changed since the last search.
Added a test case for the other error.

Spatial indexes were not checking for out-of-record condition in
the handler next command when the previous command didn't found
rows.

Fixed by making the rtree index to check for end of rows condition
before re-using the key from the previous search.

Fixed another crash if the tree has changed since the last search.
Added a test case for the other error.

            consider clustered primary keys

Choosing a shortest index for the covering index scan,
the optimizer ignored the fact, that the clustered primary
key read involves whole table data.

The find_shortest_key function has been modified to
take into account that fact that a clustered PK has a
longest key of possible covering indices.

 for ORDER BY on a TEXT or VARCHAR field" backported to 5.1.

           + failing statements

Implicit DROP event for temporary table is not getting
LOG_EVENT_THREAD_SPECIFIC_F flag, because, in the previous
executed statement in the same thread, which might even be a
failed statement, the thread_specific_used flag is set to
FALSE (in mysql_reset_thd_for_next_command) and not set to TRUE
before connection is shutdown. This means that implicit DROP
event will take the FALSE value from thread_specific_used and
will not set LOG_EVENT_THREAD_SPECIFIC_F in the event header. As
a consequence, mysqlbinlog will not print the pseudo_thread_id
from the DROP event, because one of the requirements for the
printout is that this flag is set to TRUE.

We fix this by setting thread_specific_used whenever we are
binlogging a DROP in close_temporary_tables, and resetting it to
its previous value afterward.

If an outer query is broken, a subquery might not even get set up.
EXPLAIN EXTENDED did not expect this and merrily tried to de-ref all
of the half-setup info.

We now catch this case and print as much as we have, as it doesn't cost us
anything (doesn't make regular execution slower).

backport from 5.1

      
This patch fixes some typos and poorly formulated sentences in
the output from mysqld --help --verbose.

Some of the problems described in the bug report are already
handled by the patch for Bug#49447, and are therefore not
included in this patch.

START SLAVE UNTIL MASTER ... specifies only SQL thread to stop.
rpl_slave_skip erronously deployed waiting for stop of both threads.

Corrected with deploying the correct macro.
Notice, earlier a similar bug@47749 was fixed in mysql-trunk.

for same data when using bit fields

Problem: checksum for BIT fields may be computed incorrectly 
in some cases due to its storage peculiarity.

Fix: convert a BIT field to a string then calculate its checksum.

disabling the test to not run on PB

POSIX standard, reinitialization of a pthread_once is a gray
area, but it is needed to support subsequent initializations
of the client library.

A client doing multiple mysql_library_init() and
mysql_library_end() calls over the lifetime of the process may
experience lost character set data, potentially even a
SIGSEGV.

This patch reinstates the reloading of character set data when
a mysql_library_init() is done after a mysql_library_end().

Item_field::print method does not take into
account fields whose values may be null.
The fix is to print 'NULL' if field value is null.