frm and data files for tables created by earlier MySQL
versions becomes out of sync after certain ALTER TABLE statements:
- One that changes column default value;
- One that changes table comment;
- One that changes table password.

As a result one can expirience either server crash or data corruption/loss.

This fix ensures that running ALTER TABLE on tables created by earlier
MySQL versions recreates data files.

into  neptunus.(none):/home/msvensson/mysql/my50-bug19190

Fixes for Bug#12429: Replication tests fail: "Slave_IO_Running" (?) differs related to MySQL 4.1
and Bug#16920 rpl_deadlock_innodb fails in show slave status (reported for MySQL 5.1)

into  three.local.lan:/home/matthias/Arbeit/mysql-5.0/src-1

into  mysql.com:/usr/local/home/marty/MySQL/mysql-5.0

into  three.local.lan:/home/matthias/Arbeit/mysql-5.0/src-1

  Remove duplicate test case for bug#14169

into  rurik.mysql.com:/home/igor/dev/mysql-5.0-0

into  rurik.mysql.com:/home/igor/dev/mysql-5.0-0

Temporarily commented out a query from the test case for bug 14169 to make it pass with --ps-protocol.

into  rurik.mysql.com:/home/igor/dev/mysql-4.1-2

into  mysql.com:/home/jimw/my/mysql-5.0-clean

into moonbone.local:/work/14169-bug-4.1-mysql

  Corrected test case for the bug#14169 to make it pass in --ps-protocol mode.

After a locking error the open table(s) were not fully
cleaned up for reuse. But they were put into the open table
cache even before the lock was tried. The next statement
reused the table(s) with a wrong lock type set up. This
tricked MyISAM into believing that it don't need to update
the table statistics. Hence CHECK TABLE reported a mismatch
of record count and table size.

Fortunately nothing worse has been detected yet. The effect
of the test case was that the insert worked on a read locked
table. (!)

I added a new function that clears the lock type from all
tables that were prepared for a lock. I call this function
when a lock failes.

No test case. One test would add 50 seconds to the
test suite. Another test requires file mode modifications.
I added a test script to the bug report. It contains three
cases for failing locks. All could reproduce a table
corruption. All are fixed by this patch.

This bug was not lock timeout specific.

into  mysql.com:/home/stewart/Documents/MySQL/5.0/merge

The bug caused a reported index corruption in the cases when
key_cache_block_size was not a multiple of myisam_block_size,
e.g. when key_cache_block_size=1536 while myisam_block_size=1024.

into  mysql.com:/home/matthias/Arbeit/mysql-5.0/src-1

into  mysql.com:/home/stewart/Documents/MySQL/5.0/merge

into  mysql.com:/home/stewart/Documents/MySQL/4.1/merge

into  mysql.com:/home/stewart/Documents/MySQL/4.1/merge

into  zippy.(none):/home/cmiller/work/mysql/mysql-5.0__ready

into  zippy.(none):/home/cmiller/work/mysql/mysql-5.0__ready

  Testsuite added

  5.0 additional fix for b#18691
  Handle DECIMAL the same with INT and REAL.

into  mysql.com:/usr/home/bar/mysql-5.0

does not have "NOT NULL" attribute set.  Also, calculate the padding
characters more safely, so that a negative number doesn't cause it to 
print MAXINT-n spaces.

into  april.(none):/home/svoj/devel/mysql/BUG17917/mysql-5.0

into moonbone.local:/work/14169-bug-4.1-mysql

removing comments from the opt file.

into  mysql.com:/usr/home/bar/mysql-4.1.b18691

into  sanja.is.com.ua:/home/bell/mysql/bk/work-5.0

into  mysql.com:/opt/local/work/mysql-5.0-runtime-merge

into  sanja.is.com.ua:/home/bell/mysql/bk/work-5.0

into  mysql.com:/opt/local/work/mysql-5.0-runtime-merge

into  three.local.lan:/home/matthias/Arbeit/mysql-5.0/src-1