Field_varstring::store
      
The code that temporary saved the bitmaps of the read set and the write set so that
it can set it to all columns for debug purposes was not expecting that the
table->read_set and table->write_set can be the same. And was always saving both in 
sequence.
As a result the original value was never restored.
Fixed by saving & restoring the original value only once if the two sets are the
same (in a special set of functions).

no conflicts

if table has bit fields then uneven bits(if exist) are stored into null bits place.
So we need to copy null bits in case of uneven bit field presence.

added ability for TINY[MEDIUM] text fields 
to be converted to greater subtype during
alter if necessary(altered charset)

the patch manually to another tree. 

the problem: FORMAT func max_length value was calculated incorrectly
the fix: correct calculation of max_length

show default value for BIT field in printable format

reset diagnostics area state after error message is sent

    modifying the original fix.
    As it turned out --fix-db-names option of the mysqlcheck suppress
    the --check_upgrade option, so we have to call the mysqlcheck twice
    from the mysql_upgrade.

per-file comments:
  client/mysql_upgrade.c
Bug#35934      mysql_upgrade calls mysqlcheck with insufficient parameters

The reason for the failures was bug #21205 (fixed in 6.0 by dtoa, but still present in 5.0/5.1).

Nothing to do, was already in 5.1

binlog_row_mix_innodb_myisam resutls are corrected.
The last operations prior the dup error is
TRUNCATE table t2;
Therefore after
--error ER_DUP_ENTRY
INSERT INTO t2 select * from t1;
table t2 must be empty, and that is what the updated results confirm.

Extending bug#40221 regression test: 1. include INSERT 2. convert prim key + autoinc to
unique.