anchor.diff:    # unstable does not require bs1770gain[2].
     # [1]: https://discourse.beets.io/t/forming-a-beets-core-team/639
     # [2]: https://github.com/NixOS/nixpkgs/pull/90504
  -  version = "unstable-2021-01-29";
  +  version = "unstable-2021-03-08";
   
     src = fetchFromGitHub {
       owner = "beetbox";
       repo = "beets";
  -    rev = "04ea754d00e2873ae9aa2d9e07c5cefd790eaee2";
  -    sha256 = "sha256-BIa3hnOsBxThbA2WCE4q9eaFNtObr3erZBBqobVOSiQ=";
  +    rev = "debd382837ef1d30574c2234710d536bb299f979";
  +    sha256 = "sha256-I6ejW3f72fdzWoz7g4n8pDYz2NiHGrorLegUQhQOSiI=";
     };
   
     propagatedBuildInputs = [
  
positive.code:     pythonPackages.confuse
      pythonPackages.mediafile
      gobject-introspection
    ] ++ lib.optional enableAbsubmit      essentia-extractor
      ++ lib.optional enableAcoustid      pythonPackages.pyacoustid
      ++ lib.optional enableBeatport      pythonPackages.requests_oauthlib
      ++ lib.optional (enableFetchart
                || enableDeezer
                || enableEmbyupdate
                || enableKodiupdate
                || enableLoadext
                || enablePlaylist
                || enableSubsonicplaylist
                || enableSubsonicupdate
                || enableAcousticbrainz)
                                      pythonPackages.requests
      ++ lib.optional enableCheck         beetsExternalPlugins.check
      ++ lib.optional enableConvert       ffmpeg
      ++ lib.optional enableDiscogs       pythonPackages.discogs_client
      ++ lib.optional enableKeyfinder     keyfinder-cli
      ++ lib.optional enableLastfm        pythonPackages.pylast
      ++ lib.optional enableMpd           pythonPackages.mpd2
      ++ lib.optional enableSonosUpdate   pythonPackages.soco
      ++ lib.optional enableThumbnails    pythonPackages.pyxdg
      ++ lib.optional enableWeb           pythonPackages.flask
      ++ lib.optional enableAlternatives  beetsExternalPlugins.alternatives
      ++ lib.optional enableCopyArtifacts beetsExternalPlugins.copyartifacts
      ++ lib.optional enableExtraFiles    beetsExternalPlugins.extrafiles
    ;
  
    buildInputs = [
  
negative.code:   optionalPlugins = {
      absubmit = enableAbsubmit;
      acousticbrainz = enableAcousticbrainz;
      aura = enableAura;
      badfiles = enableBadfiles;
      beatport = enableBeatport;
      bpsync = enableBpsync;
  