Revert "pythonPackages.flaky: 3.5.3 -> 3.6.1 (#68411)"

This reverts commit 755c9f3ba2.
I'm moving this to the staging-19.09 branch, similarly to a95a53aa.
It's a huge rebuild (on the order of 20k jobs), and it seems like that
was not noticed, and I can't see sufficient motivation to skip ahead of
other changes in staging-19.09.  Here my motivation is mainly to reduce
the total amount of work necessary for Hydra.

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

@@ -2,29 +2,22 @@
 , buildPythonPackage
 , fetchPypi
 , mock
-, nose
 , pytest
 }:
 
 buildPythonPackage rec {
   pname = "flaky";
-  version = "3.6.1";
+  version = "3.5.3";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "8cd5455bb00c677f787da424eaf8c4a58a922d0e97126d3085db5b279a98b698";
+    sha256 = "12bd5e41f372b2190e8d754b6e5829c2f11dbc764e10b30f57e59f829c9ca1da";
   };
 
-  checkInputs = [ mock nose pytest ];
+  buildInputs = [ mock pytest ];
 
-  checkPhase = ''
-    # based on tox.ini
-    pytest -k 'example and not options' --doctest-modules test/test_pytest/
-    pytest -k 'example and not options' test/test_pytest/
-    pytest -p no:flaky test/test_pytest/test_flaky_pytest_plugin.py
-    nosetests --with-flaky --force-flaky --max-runs 2 test/test_nose/test_nose_options_example.py
-    pytest --force-flaky --max-runs 2  test/test_pytest/test_pytest_options_example.py
-  '';
+  # waiting for feedback https://github.com/box/flaky/issues/97
+  doCheck = false;
 
   meta = with stdenv.lib; {
     homepage = https://github.com/box/flaky;