fix different travis-ci flake8 warning
fix different travis-ci flake8 warning

diego-plan9/beets,sampsyo/beets,jcoady9/beets,pkess/beets,parapente/beets,ibmibmibm/beets,shamangeorge/beets,mried/beets,madmouser1/beets,MyTunesFreeMusic/privacy-policy,swt30/beets,SusannaMaria/beets,diego-plan9/beets,mosesfistos1/beetbox,Kraymer/beets,beetbox/beets,xsteadfastx/beets,sampsyo/beets,beetbox/beets,pkess/beets,SusannaMaria/beets,diego-plan9/beets,Freso/beets,swt30/beets,MyTunesFreeMusic/privacy-policy,mried/beets,sampsyo/beets,shamangeorge/beets,parapente/beets,jcoady9/beets,SusannaMaria/beets,madmouser1/beets,SusannaMaria/beets,lengtche/beets,artemutin/beets,swt30/beets,mried/beets,xsteadfastx/beets,shamangeorge/beets,lengtche/beets,parapente/beets,Freso/beets,Kraymer/beets,madmouser1/beets,sampsyo/beets,ibmibmibm/beets,ibmibmibm/beets,jackwilsdon/beets,beetbox/beets,artemutin/beets,artemutin/beets,MyTunesFreeMusic/privacy-policy,jcoady9/beets,diego-plan9/beets,Kraymer/beets,artemutin/beets,shamangeorge/beets,xsteadfastx/beets,jackwilsdon/beets,mried/beets,ibmibmibm/beets,MyTunesFreeMusic/privacy-policy,mosesfistos1/beetbox,beetbox/beets,lengtche/beets,Freso/beets,Kraymer/beets,pkess/beets,mosesfistos1/beetbox,madmouser1/beets,pkess/beets,mosesfistos1/beetbox,parapente/beets,swt30/beets,jackwilsdon/beets,lengtche/beets,jackwilsdon/beets,jcoady9/beets,Freso/beets,xsteadfastx/beets