The problem was that bits of the destructive equality propagation
optimization weren't being undone after the execution of a stored
program. Modifications to the parse tree that are based on transient
properties must be undone to enable the re-execution of stored
programs.

The solution is to cleanup any references to predicates generated
by the equality propagation during the execution of a stored program.

mysql-test/r/trigger.result:
  Add test case result for Bug#51650.
mysql-test/t/trigger.test:
  Add test case for Bug#51650.
sql/item.cc:
  Remove reference to a equality predicate.

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.


mysql-test/r/innodb_mysql.result:
  Test case for bug #39653.
mysql-test/t/innodb_mysql.test:
  Test case for bug #39653.
sql/sql_select.cc:
  Bug #39653: find_shortest_key in sql_select.cc does not
              consider clustered primary keys
  
  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

mysql-test/r/explain.result:
  Show that EXPLAIN EXTENDED with subquery and illegal out query doesn't crash.
  Show also that SHOW WARNINGS will render an additional Note in the hope of
  being, well, helpful.
mysql-test/t/explain.test:
  If we have only half a query for EXPLAIN EXTENDED to print (i.e.,
  incomplete subquery info as outer query is illegal), we should
  provide the user with as much info as we easily can if they ask
  for it. What we should not do is crash when they come asking for
  help, that violates etiquette in some countries.
sql/item_subselect.cc:
  If the sub-query's actually set up, print it. Otherwise, elide.

      
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.

mysql-test/suite/rpl/t/rpl_slave_skip.test:
  changing two waiting calls for offline of both threads into waiting for SQL to stop.

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.


mysql-test/r/myisam.result:
  Fix for bug#51304: checksum table gives different results 
  for same data when using bit fields
    - test result.
mysql-test/t/myisam.test:
  Fix for bug#51304: checksum table gives different results 
  for same data when using bit fields
    - test case.
sql/sql_table.cc:
  Fix for bug#51304: checksum table gives different results 
  for same data when using bit fields
    - convert BIT fields to strings calculating its checksums
  as some bits may be saved among NULL bits in the record buffer.

disabling the test to not run on PB

mysql-test/t/mysql_upgrade.test:
  For execution, mostly testing the presence of the binary anyway.

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

mysys/charset.c:
  Reinitialize a pthread_once_t variable.

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.


mysql-test/r/explain.result:
  test case
mysql-test/r/func_str.result:
  result fix
mysql-test/r/having.result:
  result fix
mysql-test/r/select.result:
  result fix
mysql-test/r/subselect.result:
  result fix
mysql-test/r/union.result:
  result fix
mysql-test/t/explain.test:
  test case
sql/item.cc:
  print 'NULL' if field value is null.