Steps to reproduce:
1. Enable a custom resource pack that replaces the .oggs for music discs.
2. Put a music disc in a Jukebox.
3. Observe that the jukebox plays the custom music, but stops playing (and outputting a redstone signal) when the duration of the default music is complete, rather than the duration of the custom music. If the custom track is longer than the default, this leads to the song being truncated and stopping early.