This fixed a bug in GROUP BY on a BLOB column with NULL values.


myisam/mi_create.c:
  Fixed max_key_length when using UNIQUE keys.
myisam/mi_unique.c:
  Simple optimization
  Make different CRC for keys with null and empty strings.
mysql-test/r/group_by.result:
  Updated results
mysql-test/t/group_by.test:
  Test of bug