Updated MySQL time handling code to react correctly on UTC leap second additions.
MySQL functions that return the OS current time, like e.g. CURDATE(), NOW() etc
will return :59:59 instead of :59:60 or 59:61.
As a result the reader will receive :59:59 for 2 or 3 consecutive seconds 
during the leap second.
This fix will not affect the values returned by UNIX_TIMESTAMP() for leap seconds.
But note that when converting the value returned by UNIX_TIMESTAMP() to broken 
down time the correction of leap seconds will still be applied.
Note that this fix will make a difference *only* if the OS is specially configured
to return leap seconds from the OS time calls or when using a MySQL time zone 
defintion that has leap seconds.
Even after this change date/time literals (or other broken down time 
representations) with leap seconds (ending on :59:60 or 59:61) will still be 
considered illegal and discarded by the server with an error or 
a warning depending on the sql mode.
Added a test case to demonstrate the effect of the fix.

by using and taking out a full path.

TABLE_LIST doesn't free Strings in its string lists
(TABLE_LIST::use_index and TABLE_liST::ignore_index), so
calling c_ptr_safe() on that Strings leads to memleaks.
OTOH "safe" c_ptr_safe() is not necessary there and we can
replace it with c_ptr().

Diff to actual 5.0-bugteam is revno: 2725 only

            an error

Even after the fix for bug 28701 visible behaviors of
SELECT FROM a view and SELECT FROM a regular table are
little bit different:

1. "SELECT FROM regular table USE/FORCE/IGNORE(non
   existent index)" fails with a "ERROR 1176 (HY000):
   Key '...' doesn't exist in table '...'"

2. "SELECT FROM view USING/FORCE/IGNORE(any index)" fails
   with a "ERROR 1221 (HY000): Incorrect usage of
   USE/IGNORE INDEX and VIEW".  OTOH "SHOW INDEX FROM
   view" always returns empty result set, so from the point
   of same behaviour view we trying to use/ignore non
   existent index.

To harmonize the behaviour of USE/FORCE/IGNORE(index)
clauses in SELECT from a view and from a regular table the
"ERROR 1221 (HY000): Incorrect usage of USE/IGNORE INDEX
and VIEW" message has been replaced with the "ERROR 1176
(HY000): Key '...' doesn't exist in table '...'" message
like for tables and non existent keys.

      
The SHOW VARIABLES LIKE .../SELECT @@/SELECT ... FROM INFORMATION_SCHEMA.VARIABLES
were assuming that all the system variables are in system charset (UTF-8).
However the variables that are settable through command line will have a different
character set (character_set_filesystem).
Fixed the server to remember the correct character set of basedir, datadir, tmpdir,
ssl, plugin_dir, slave_load_tmpdir, innodb variables; init_connect and init_slave 
variables and use it when processing data.

The bug is repeatable with latest(1.0.1) InnoDB plugin on Linux, Win,
If MySQL is compiled with valgrind there are errors about
using of uninitialized variable(orig_table).
The fix is to set field->orig_table correct value.

enable uncacheable flag if we update a view with check option
and check option has a subselect, otherwise, the check option
can be evaluated after the subselect was freed as independent
(See full_local in JOIN::join_free())

set DATE|DATETIME value to 0 if ALLOW_INVALID_DATES sql_mode is not enabled.

extended perror to enable printing of Win32 system errors

We pretended that TIMEDIFF() would always return positive results;
this gave strange results in comparisons of the TIMEDIFF(low,hi)<TIME(0)
type that rendered a negative result, but still gave false in comparison.
We also inadvertantly dropped the sign when converting times to
decimal.

CAST(time AS DECIMAL) handles signs of the times correctly.
TIMEDIFF() marked up as signed. Time/date comparison code switched to
signed for clarity.

Problem: in 5.0 'check table for upgrade' doesn't detect
incompatible collation changes made in 5.0.48.

Fix: backport #39585 fix to 5.0

Altering how MTR checks global variable status to exclude timestamp
Changed SQL statements to update style.

ONLY_FULL_GROUP_BY

The check for non-aggregated columns in queries with aggregate function, but without
GROUP BY was treating all the parts of the query as if they are in the SELECT list.
Fixed by ignoring the non-aggregated fields in the WHERE clause.

the problem is the same as reported in bug#20835,
so the fix is backport of bug#20835 patch.

returns truncated results

Problem: performig conversion from {INT, DECIMAL, REAL} to CHAR
we incorrectly set its max length in some cases that may lead
to truncated results returned.

Fix: properly set CONVERT({INT, DECIMAL, REAL}, CHAR) result's
max length.

Problem: memory leak occurs when we open a federated table
that has its share in the hash.

Fix: free not used memory.

Note: the fix should NOT be merged to 5.1 (the code changed).

The test itself is not faulty. The testcase timeout
problem happens if this IMHO mid size resource
(space in vardir, virtual memory, amount of disk I/O)
consuming test meets a weak (excessive disk I/O caused
by parallel applications or paging) testing box.

The modifications:
- Move the most time and disk I/O consuming subtest
  for Bug 1820 into its own script (multi_update2)
  This will reduce the likelihood that we exceed the
  testcase timeout.
- Replace error numbers with error names
- Minor improvements of the formatting

- 

Item_func_div didn't calculate the precision of the result properly.
  The result of 5/0.0001 is 5000 so we have to add decimals of the divisor
  to the planned precision.

per-file comments:
  mysql-test/r/type_newdecimal.result
Bug#31616 div_precision_increment description looks wrong
    test result fixed

  mysql-test/t/type_newdecimal.test
Bug#31616 div_precision_increment description looks wrong
    test case

  sql/item_func.cc
Bug#31616 div_precision_increment description looks wrong
    precision must be increased with args[1]->decimals parameter

            missing after downgrade

Obsolete arc/ directory and view .frm file backup support
has been removed by the patch for bug 17823. However, that
bugfix caused a problem with "live downgrades" of the
server: if we rename some view 4 times under 5.1.29/5.0.72
and then try to rename it under 5.1.28/5.0.70 on the same
database, the server fails with a error:

  query 'RENAME TABLE ... TO ...' failed: 6: Error on
  delete of '....frm-0001' (Errcode: 2)

Also .frm file of that view may be lost (renamed to .frm~).

The server failed because it tried to rename latest 3
backup .frm files renaming the view: the server used an
integer value of the "revision" field of .frm file to
extract those file names. After the fix for bug 17823 those
files were not created/maintained any more, however the
"revision" field was incremented as usual. So, the server
failed renaming non existent files.

This fix solves the problem by removing the support for
"revision" .frm file field:
1. New server silently ignores existent "revision" fields
   in old .frm files and never write it down;
2. Old server assumes, that missing "revision" field in new
   .frm files means default value of 0.
3. Accordingly to the fix for bug 17823 the new server
   drops arc/ directory on alter/rename view, so after
   "live downgrade" old server begins maintenance of the
   arc/ directory from scratch without conflicts with .frm
   files.

tables can cause server to crash!

The bug will be fixed by patch for #34779: "crash in checksum table
on federated tables with blobs containing nulls"

Only a test case commited.