oslo-config: 4.11.0 -> 4.12.0, fix build

also updated the following dependencies:
keystoneauth1: 3.1.0 -> 3.2.0
  disabled tests which require oslo-config, oslo-test or requests-kerberos
oslo-i18n: 2.7.0 -> 3.18.0
oslotest: 1.12.0 -> 2.18.0
os-client-config: 1.8.1 -> 1.28.0
  needed to disable testing due to circular dependency with oslotest
mox3: 0.11.0 -> 0.23.0
  disable tests for py36 due to upstream bug
debtcollector: 0.9.0 -> 1.17.0
  tests enabled

extra packages:
requestsexceptions: init at 1.3.0

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

@@ -0,0 +1,27 @@
+{ lib, buildPythonPackage, fetchPypi, pbr }:
+
+buildPythonPackage rec {
+  pname = "requestsexceptions";
+  version = "1.3.0";
+  name = "${pname}-${version}";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "0gim00vi7vfq16y8b9m1vpy01grqvrdrbh88jb98qx6n6sk1n54g";
+  };
+
+  propagatedBuildInputs = [ pbr ];
+
+  # upstream hacking package is not required for functional testing
+  patchPhase = ''
+    sed -i '/^hacking/d' test-requirements.txt
+  '';
+
+  meta = with lib; {
+    description = "Import exceptions from potentially bundled packages in requests.";
+    homepage = "https://pypi.python.org/pypi/requestsexceptions";
+    license = licenses.asl20;
+    maintainers = with maintainers; [ makefu ];
+    patforms = platforms.all;
+  };
+}