pkgs/development/python-modules/pygobject: ensure that python code can be found

svn path=/nixpkgs/trunk/; revision=23616

pkgs/development/python-modules/pygobject/default.nix

@@ -8,4 +8,16 @@ stdenv.mkDerivation {
   };
 
   buildInputs = [python pkgconfig glib];
+
+  postInstall = ''
+    # All python code is installed into a "gtk-2.0" sub-directory. That
+    # sub-directory may be useful on systems which share several library
+    # versions in the same prefix, i.e. /usr/local, but on Nix that directory
+    # is useless. Furthermore, its existence makes it very hard to guess a
+    # proper $PYTHONPATH that allows "import gtk" to succeed.
+    cd $(toPythonPath $out)/gtk-2.0
+    for n in *; do
+      ln -s "gtk-2.0/$n" "../$n"
+    done
+  '';
 }