First one is related to Bug#7905. One should not be allowed to
create new user with password without UPDATE privilege to
MySQL database. Furthermore, executing the same GRANT statement
twice would actually crash the server and corrupt privilege database.

Other bug was that one could update a column, using the existing
value as basis to calculate the new value (e.g. UPDATE t1 SET a=a+1)
without SELECT privilege to the field (a in the above example)

Fixed tests grant.pl and grant2, which were wrong.