Music Disc keeps playing when extracted with hopper minecart

(Both are Droppers facing to the right - Minecart with a hopper is on a default rail)

 

When placing a music disc into the left dropper and pushing the button, the disc starts playing and gets extracted at the same time - but still keeps playing.

Even after placing a new disc or breaking the jukebox, the music continues and can only be stopped with /stopsound.

Expected bevaviour:
The music disc moves directly into the minecart and does not continue to play.