To Reproduce:

1. Play any music on an AppleTV
(Only way to do this, that I've found, is to us Home Share from your Mac (just enable it in iTunes), because Apple Music doesn't seem to be working on tvOS yet and you can't connect the device to iTunes directly)

2. Build the attached App (make sure that "override iPod music" is turned off).

3. Deploy to AppleTV, observe that music stops after launch and you can only here the sound played by the app.

Not reproducible on iOS with trunk, but reproducible on:

Version 5.3.0b3 (9b3031f5d494)
Mon, 12 Oct 2015 15:58:11 GMT
Branch: platform/ios/avaudiosession