virt-manager: Fix error: 'ImportError: No module named libvirt'

The problem was that libvirt 1.2.0 no longer includes the python bindings; it is
a separate package now.

pkgs/applications/virtualization/virt-manager/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, pythonPackages, intltool, libvirt, libxml2Python, curl,
+{ stdenv, fetchurl, pythonPackages, intltool, libxml2Python, curl,
   python, makeWrapper, virtinst, pyGtkGlade, pythonDBus, gnome_python, gtkvnc, vte}:
 
 with stdenv.lib;
@@ -18,13 +18,13 @@ stdenv.mkDerivation rec {
       paste_deploy m2crypto ipy boto_1_9 twisted sqlalchemy_migrate
       distutils_extra simplejson readline glance cheetah lockfile httplib2
       # !!! should libvirt be a build-time dependency?  Note that
-      # libxml2Python is a dependency of libvirt.py. 
+      # libxml2Python is a dependency of libvirt.py.
       libvirt libxml2Python urlgrabber virtinst pyGtkGlade pythonDBus gnome_python
       gtkvnc vte
     ];
 
   buildInputs =
-    [ pythonPackages.python 
+    [ pythonPackages.python
       pythonPackages.wrapPython
       pythonPackages.mox
       pythonPackages.urlgrabber
@@ -36,7 +36,7 @@ stdenv.mkDerivation rec {
     ] ++ pythonPath;
 
   buildPhase = "make";
-  
+
   nativeBuildInputs = [ makeWrapper pythonPackages.wrapPython ];
 
   # patch the runner script in order to make wrapPythonPrograms work and run the program using a syscall

pkgs/top-level/python-packages.nix

@@ -8195,7 +8195,29 @@ pythonPackages = modules // import ./python-packages-generated.nix {
       description = "A logging replacement for Python";
       license = pkgs.lib.licenses.bsd3;
     };
- };
+  };
+
+  libvirt = pkgs.stdenv.mkDerivation rec {
+    name = "libvirt-python-${version}";
+    version = "1.2.0";
+
+    src = fetchurl {
+      url = "http://libvirt.org/sources/python/${name}.tar.gz";
+      sha256 = "0azml1yv9iqnpj4sdg1wwsa70q7kb06lv85p63qwyd8vrd0y7rrg";
+    };
+
+    buildInputs = [ python pkgs.pkgconfig pkgs.libvirt lxml ];
+
+    buildPhase = "python setup.py build";
+
+    installPhase = "python setup.py install --prefix=$out";
+
+    meta = {
+      homepage = http://www.libvirt.org/;
+      description = "libvirt Python bindings";
+      license = "LGPLv2";
+    };
+  };
 
 # python2.7 specific eggs
 } // pkgs.lib.optionalAttrs (python.majorVersion == "2.7") {