Add test for custom named music section (`library_name` property) (#1595)
Add test for custom named music section (`library_name` property) (#1595)

swt30/beets,parapente/beets,swt30/beets,lightwang1/beets,Freso/beets,swt30/beets,lightwang1/beets,marcuskrahl/beets,mosesfistos1/beetbox,marcuskrahl/beets,artemutin/beets,shamangeorge/beets,tima/beets,mosesfistos1/beetbox,marcuskrahl/beets,jcoady9/beets,parapente/beets,beetbox/beets,sampsyo/beets,swt30/beets,marcuskrahl/beets,parapente/beets,diego-plan9/beets,xsteadfastx/beets,LordSputnik/beets,asteven/beets,shamangeorge/beets,sadatay/beets,m-urban/beets,jackwilsdon/beets,asteven/beets,diego-plan9/beets,Freso/beets,MyTunesFreeMusic/privacy-policy,m-urban/beets,sadatay/beets,lengtche/beets,madmouser1/beets,artemutin/beets,LordSputnik/beets,YetAnotherNerd/beets,MyTunesFreeMusic/privacy-policy,YetAnotherNerd/beets,YetAnotherNerd/beets,SusannaMaria/beets,sadatay/beets,beetbox/beets,mosesfistos1/beetbox,SusannaMaria/beets,asteven/beets,tima/beets,kelvinhammond/beets,jackwilsdon/beets,mried/beets,lengtche/beets,kareemallen/beets,mried/beets,tima/beets,asteven/beets,m-urban/beets,mosesfistos1/beetbox,parapente/beets,beetbox/beets,diego-plan9/beets,xsteadfastx/beets,LordSputnik/beets,drm00/beets,kareemallen/beets,lightwang1/beets,kareemallen/beets,pkess/beets,diego-plan9/beets,YetAnotherNerd/beets,SusannaMaria/beets,ibmibmibm/beets,Kraymer/beets,jcoady9/beets,sampsyo/beets,kelvinhammond/beets,kareemallen/beets,jcoady9/beets,Kraymer/beets,beetbox/beets,drm00/beets,SusannaMaria/beets,jmwatte/beets,kelvinhammond/beets,Freso/beets,ibmibmibm/beets,Freso/beets,sampsyo/beets,drm00/beets,lengtche/beets,lengtche/beets,jmwatte/beets,ibmibmibm/beets,artemutin/beets,ibmibmibm/beets,artemutin/beets,mried/beets,Kraymer/beets,jcoady9/beets,drm00/beets,pkess/beets,MyTunesFreeMusic/privacy-policy,xsteadfastx/beets,jackwilsdon/beets,jackwilsdon/beets,pkess/beets,tima/beets,jmwatte/beets,m-urban/beets,sampsyo/beets,madmouser1/beets,jmwatte/beets,Kraymer/beets,shamangeorge/beets,kelvinhammond/beets,madmouser1/beets,mried/beets,xsteadfastx/beets,pkess/beets,MyTunesFreeMusic/privacy-policy,lightwang1/beets,LordSputnik/beets,shamangeorge/beets,sadatay/beets,madmouser1/beets