fix tests, list of allowed commands have changed (redis 3.0.6)

[remicollet]

Detected in Fedora QA, broken since redis 3.0.6

See https://apps.fedoraproject.org/koschei/package/php-nrk-Predis

 There were 2 failures:
 1) Predis\Command\PubSubSubscribeByPatternTest::testCannotSendOtherCommandsAfterPsubscribe
 Failed asserting that exception message 'ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / PING / QUIT allowed in this context' contains 'ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / QUIT allowed in this context'.
 2) Predis\Command\PubSubSubscribeTest::testCannotSendOtherCommandsAfterSubscribe
 Failed asserting that exception message 'ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / PING / QUIT allowed in this context' contains 'ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / QUIT allowed in this context'.
 FAILURES!

[remicollet]

In build history (https://apps.fedoraproject.org/koschei/package/php-nrk-Predis) you will notice build failure since redis 3.0.6 (2015-12-19 02:23:40), and back to normal since this patch is applied (2015-12-28 09:44:30)