Whoever passes the Turing test is a liar

An Asimoivan robot wouldn't pass the Turing test. In order to pass the test, and thus be deemed a true sentient being, the robot would have to lie about its nature. This is forbidden by the second law of robotics.

Unless, of course, the tester was not a human but a fellow robot, with all possible interesting definitions of "sentient" and "human" that might show up in that conversation.