Don't fail on GStreamer EOS if no backend is running
Don't fail on GStreamer EOS if no backend is running

This removes the printed AssertionError when running
ScannerTest.test_data_is_set()

bacontext/mopidy,abarisain/mopidy,hkariti/mopidy,jodal/mopidy,ali/mopidy,dbrgn/mopidy,bencevans/mopidy,vrs01/mopidy,glogiotatidis/mopidy,dbrgn/mopidy,kingosticks/mopidy,jcass77/mopidy,priestd09/mopidy,jcass77/mopidy,swak/mopidy,quartz55/mopidy,pacificIT/mopidy,jmarsik/mopidy,mopidy/mopidy,abarisain/mopidy,quartz55/mopidy,woutervanwijk/mopidy,tkem/mopidy,swak/mopidy,tkem/mopidy,SuperStarPL/mopidy,mokieyue/mopidy,quartz55/mopidy,vrs01/mopidy,bencevans/mopidy,SuperStarPL/mopidy,quartz55/mopidy,jmarsik/mopidy,bencevans/mopidy,vrs01/mopidy,kingosticks/mopidy,jodal/mopidy,rawdlite/mopidy,ZenithDK/mopidy,ali/mopidy,priestd09/mopidy,rawdlite/mopidy,ali/mopidy,SuperStarPL/mopidy,swak/mopidy,liamw9534/mopidy,rawdlite/mopidy,bacontext/mopidy,mopidy/mopidy,ali/mopidy,adamcik/mopidy,bencevans/mopidy,priestd09/mopidy,ZenithDK/mopidy,bacontext/mopidy,SuperStarPL/mopidy,glogiotatidis/mopidy,mokieyue/mopidy,jcass77/mopidy,adamcik/mopidy,dbrgn/mopidy,liamw9534/mopidy,mokieyue/mopidy,bacontext/mopidy,mokieyue/mopidy,kingosticks/mopidy,adamcik/mopidy,dbrgn/mopidy,mopidy/mopidy,diandiankan/mopidy,pacificIT/mopidy,pacificIT/mopidy,woutervanwijk/mopidy,diandiankan/mopidy,glogiotatidis/mopidy,vrs01/mopidy,ZenithDK/mopidy,hkariti/mopidy,jodal/mopidy,hkariti/mopidy,glogiotatidis/mopidy,rawdlite/mopidy,swak/mopidy,pacificIT/mopidy,hkariti/mopidy,ZenithDK/mopidy,tkem/mopidy,jmarsik/mopidy,tkem/mopidy,jmarsik/mopidy,diandiankan/mopidy,diandiankan/mopidy