Test failure on image #138 mako

[Victor Thompson]

test_pressing_prev_from_first_song_plays_last_when_repeat_on fails on the Utopic image #138 tests [1].

Additionally, this test, and test_pressing_next_from_last_song_plays_first_when_repeat_on, have a somewhat inaccurate testing intent. Pressing previous/next to loop to the end/beginning of the queue should work regardless of whether repeat is on. A better test would be to ensure this behavior works when repeat is OFF. The test name should omit "when_repeat_on".

[1] http://ci.ubuntu.com/smokeng/utopic/touch/mako/138:20140718:20140717.1/9126/music_app/1388910/