for ENGINE=MRG_MYISAM (should be optimized out).

Before WL#3281 MERGE engine had the HA_NOT_EXACT_COUNT flag
unset, and it worked with COUNT optimization as desired.
After the removal of the HA_NOT_EXACT_COUNT flag neither
HA_STATS_RECORDS_IS_EXACT (opposite to former HA_NOT_EXACT_COUNT
flag) nor modern HA_HAS_RECORDS flag were not added to MERGE
table flag mask.

1. The HA_HAS_RECORDS table flag has been set.
2. The ha_myisammrg::records method has been overridden to
   calculate total number of records in underlying tables.

into  host.loc:/home/uchum/work/5.1-bugteam

  Post-commit minor cleanup of testcase (bug#36139).

into  host.loc:/home/uchum/work/5.1-bugteam

into  host.loc:/home/uchum/work/5.0-bugteam

                 impossible WHERE/HAVING clause
                 (subselect_single_select_engine::exec).

Allocation and initialization of joined table list t1, t2... of
subqueries like:

    NOT IN (SELECT ... FROM t1,t2,... WHERE 0)

is optimized out, however server tries to traverse this list.

Grouping or ordering of long values in not indexed BLOB/TEXT columns
with GBK or BIG5 charsets crashes the server.

MySQL server uses sorting (the filesort procedure) in the temporary
table to evaluate the GROUP BY clause in case of lack of suitable index.
That procedure takes into account only first @max_sort_length bytes
(system variable, usually 1024) of TEXT/BLOB sorting key string.
The my_strnxfrm_gbk and my_strnxfrm_big5 fill temporary keys
with data of whole blob length instead of @max_sort_length bytes
length. That buffer overrun has been fixed.

into  mysql.com:/home/psergey/mysql-5.1-bugteam
  BUG#36139: manual merge

- Make convert_zerofill_number_to_string() take into account that the 
  constant it is converting may evaluate to NULL.

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.1-rpl-merge

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.1-rpl-merge

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.1-rpl-merge

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.0-rpl-merge

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.1-rpl-merge

into  magare.gmz:/home/kgeorge/mysql/work/merge-build-5.1-bugteam

into  mats-laptop.(none):/home/bk/b29020-mysql-5.1-rpl

tables is not zero any more. For row-based logging, there is an extra commit
for sending rows changed by the statement to the binary log.

into  magare.gmz:/home/kgeorge/mysql/work/merge-build-5.1-bugteam

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.1-rpl-merge

into  dl145h.mysql.com:/data0/mkindahl/mysql-5.0-rpl-merge

into  magare.gmz:/home/kgeorge/mysql/work/merge-build-5.1-bugteam

into  magare.gmz:/home/kgeorge/mysql/work/merge-build-5.1-bugteam

into  amd64.(none):/src/bug26243/my51-bug26243

into  mysql1000.(none):/home/andrei/MySQL/MERGE/5.1-main2rpl

If a binlog file is manually replaced with a namesake directory the internal purging did
not handle the error of deleting the file so that eventually
a post-execution guards fires an assert.

Fixed with reusing a snippet of code for bug@18199 to tolerate lack of the file but no other error 
at an attempt to delete it.
The same applied to the index file deletion.

The cset carries pieces of manual merging.

into  macbook.gmz:/Users/kgeorge/mysql/work/pb-5.1-bugteam

into  macbook.gmz:/Users/kgeorge/mysql/work/pb-5.1-bugteam

into  mysql1000.(none):/home/andrei/MySQL/MERGE/5.1-main2rpl

into  mysql1000.(none):/home/andrei/MySQL/MERGE/5.1-main2rpl

into  macbook.gmz:/Users/kgeorge/mysql/work/pb-5.1-bugteam