test: Add test for relative playlists
test: Add test for relative playlists

jackwilsdon/beets,shamangeorge/beets,ibmibmibm/beets,SusannaMaria/beets,beetbox/beets,beetbox/beets,jackwilsdon/beets,SusannaMaria/beets,SusannaMaria/beets,ibmibmibm/beets,shamangeorge/beets,ibmibmibm/beets,sampsyo/beets,shamangeorge/beets,SusannaMaria/beets,ibmibmibm/beets,jackwilsdon/beets,beetbox/beets,sampsyo/beets,beetbox/beets,sampsyo/beets,sampsyo/beets,shamangeorge/beets,jackwilsdon/beets