This would be before they reverted the Warlock, however. The playtest 7 version (which I am currently playing in a game kindly run by Hussar) still has one bonus invocation over the 5.0 Warlock--but pacts have become invocations as well. This change means that the Warlock has gained a net of exactly 1 total invocation, and that occurs (roughly) before 10th level IIRC. The 5.5e Warlock, as of playtest 7, still has Mystic Arcana, and even allows you to change what spells you picked, something you couldn't do before.