Merge change from MySQL AB:

ChangeSet@1.2616, 2007-12-01 19:55:06+01:00, tnurnberg@mysql.com +8 -0
  Bug#31177: Server variables can't be set to their current values
 
  5.1+ specific fixes (plugins etc.)

  mysql-test/r/innodb.result@1.204, 2007-12-01 19:55:04+01:00, tnurnberg@mysql.com +2 -2
    we throw warnings to the client, yea, verily