Add autobahn derivation for nixos

Copied from nixos-19.09-small/pkgs/development/python-modules/autobahn/default.nix

nix/autobahn.nix

@@ -0,0 +1,34 @@
+{ lib, buildPythonPackage, fetchPypi, isPy3k,
+  six, txaio, twisted, zope_interface, cffi, trollius, futures,
+  mock, pytest, cryptography, pynacl
+}:
+buildPythonPackage rec {
+  pname = "autobahn";
+  version = "19.8.1";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "294e7381dd54e73834354832604ae85567caf391c39363fed0ea2bfa86aa4304";
+  };
+
+  propagatedBuildInputs = [ six txaio twisted zope_interface cffi cryptography pynacl ] ++
+    (lib.optionals (!isPy3k) [ trollius futures ]);
+
+  checkInputs = [ mock pytest ];
+  checkPhase = ''
+    runHook preCheck
+    USE_TWISTED=true py.test $out
+    runHook postCheck
+  '';
+
+  # Tests do no seem to be compatible yet with pytest 5.1
+  # https://github.com/crossbario/autobahn-python/issues/1235
+  doCheck = false;
+
+  meta = with lib; {
+    description = "WebSocket and WAMP in Python for Twisted and asyncio.";
+    homepage    = "https://crossbar.io/autobahn";
+    license     = licenses.mit;
+    maintainers = with maintainers; [ nand0p ];
+  };
+}