beets: Set Python version via top-level attribute

This largely reverts commit 599312739e.

The main reason is that it breaks the plugins, because the mentioned
commit didn't change the attributes for the plugins as well.

But instead of just fixing the attributes when we import the plugin
packages, let's just override pythonPackages in all-packages.nix.

Right now, Beets is in transition to Python 3, so we don't need to wait
that long until we can remove the dependency on Python 2:

https://github.com/beetbox/beets/releases/tag/v1.4.1

Once Python 3 support is no longer beta, we can just change this by
changing one line only instead of several.

Tested this by building beets with both external plugins.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Cc: @FRidh

pkgs/tools/audio/beets/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchFromGitHub, writeScript, glibcLocales
-, python2Packages, imagemagick
+, pythonPackages, imagemagick
 
 , enableAcousticbrainz ? true
 , enableAcoustid       ? true
@@ -22,17 +22,17 @@
 , bashInteractive, bash-completion
 }:
 
-assert enableAcoustid    -> python2Packages.pyacoustid     != null;
+assert enableAcoustid    -> pythonPackages.pyacoustid     != null;
 assert enableBadfiles    -> flac != null && mp3val != null;
 assert enableConvert     -> ffmpeg != null;
-assert enableDiscogs     -> python2Packages.discogs_client != null;
-assert enableFetchart    -> python2Packages.responses      != null;
+assert enableDiscogs     -> pythonPackages.discogs_client != null;
+assert enableFetchart    -> pythonPackages.responses      != null;
 assert enableKeyfinder   -> keyfinder-cli != null;
-assert enableLastfm      -> python2Packages.pylast         != null;
-assert enableMpd         -> python2Packages.mpd            != null;
+assert enableLastfm      -> pythonPackages.pylast         != null;
+assert enableMpd         -> pythonPackages.mpd            != null;
 assert enableReplaygain  -> bs1770gain                    != null;
-assert enableThumbnails  -> python2Packages.pyxdg          != null;
-assert enableWeb         -> python2Packages.flask          != null;
+assert enableThumbnails  -> pythonPackages.pyxdg          != null;
+assert enableWeb         -> pythonPackages.flask          != null;
 
 with stdenv.lib;
 
@@ -72,7 +72,7 @@ let
   testShell = "${bashInteractive}/bin/bash --norc";
   completion = "${bash-completion}/share/bash-completion/bash_completion";
 
-in python2Packages.buildPythonApplication rec {
+in pythonPackages.buildPythonApplication rec {
   name = "beets-${version}";
   version = "1.4.1";
 
@@ -84,34 +84,34 @@ in python2Packages.buildPythonApplication rec {
   };
 
   propagatedBuildInputs = [
-    python2Packages.enum34
-    python2Packages.jellyfish
-    python2Packages.munkres
-    python2Packages.musicbrainzngs
-    python2Packages.mutagen
-    python2Packages.pathlib
-    python2Packages.pyyaml
-    python2Packages.unidecode
-  ] ++ optional enableAcoustid     python2Packages.pyacoustid
+    pythonPackages.enum34
+    pythonPackages.jellyfish
+    pythonPackages.munkres
+    pythonPackages.musicbrainzngs
+    pythonPackages.mutagen
+    pythonPackages.pathlib
+    pythonPackages.pyyaml
+    pythonPackages.unidecode
+  ] ++ optional enableAcoustid     pythonPackages.pyacoustid
     ++ optional (enableFetchart
               || enableEmbyupdate
               || enableAcousticbrainz)
-                                   python2Packages.requests2
+                                   pythonPackages.requests2
     ++ optional enableConvert      ffmpeg
-    ++ optional enableDiscogs      python2Packages.discogs_client
+    ++ optional enableDiscogs      pythonPackages.discogs_client
     ++ optional enableKeyfinder    keyfinder-cli
-    ++ optional enableLastfm       python2Packages.pylast
-    ++ optional enableMpd          python2Packages.mpd
-    ++ optional enableThumbnails   python2Packages.pyxdg
-    ++ optional enableWeb          python2Packages.flask
+    ++ optional enableLastfm       pythonPackages.pylast
+    ++ optional enableMpd          pythonPackages.mpd
+    ++ optional enableThumbnails   pythonPackages.pyxdg
+    ++ optional enableWeb          pythonPackages.flask
     ++ optional enableAlternatives (import ./alternatives-plugin.nix {
-      inherit stdenv python2Packages fetchFromGitHub;
+      inherit stdenv pythonPackages fetchFromGitHub;
     })
     ++ optional enableCopyArtifacts (import ./copyartifacts-plugin.nix {
-      inherit stdenv python2Packages fetchFromGitHub;
+      inherit stdenv pythonPackages fetchFromGitHub;
     });
 
-  buildInputs = with python2Packages; [
+  buildInputs = with pythonPackages; [
     beautifulsoup4
     imagemagick
     mock

pkgs/top-level/all-packages.nix

@@ -1018,7 +1018,9 @@ in
 
   beanstalkd = callPackage ../servers/beanstalkd { };
 
-  beets = callPackage ../tools/audio/beets { };
+  beets = callPackage ../tools/audio/beets {
+    pythonPackages = python2Packages;
+  };
 
   bgs = callPackage ../tools/X11/bgs { };