"Patch to fix bug 38551": it was a manual backport (2008-10-15) of
http://lists.mysql.com/commits/56418.
But that was an early, non-final patch from the fixer of this bug (TheK):
after that backport was made by Mikael, TheK decided to do a different fix,
which was finally pushed into 6.0.
Then 5.1's code was changed for some other reasons, so now we have a
conflict between the old never-approved TheK patch backported to Summit and
the latest 5.1. The backport cannot stay, it has to be removed due to
the conflict, and then rewritten if desired.