add compatibility to old version of musicbrainzngs
add compatibility to old version of musicbrainzngs

Signed-off-by: Shen-Ta Hsieh <0e1c526e283930e08a5f1b8bc8e252f95b527d42@gmail.com>

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