pythonPackages.pymystem3: skip tests py2

pkgs/development/python-modules/pymystem3/default.nix

@@ -1,6 +1,7 @@
 { lib
 , fetchPypi
 , buildPythonPackage
+, isPy3k
 , requests
 , flake8
 , mock
@@ -19,6 +20,7 @@ buildPythonPackage rec {
 
   propagatedBuildInputs = [ requests ];
   checkInputs = [ flake8 mock pytest ];
+  doCheck = isPy3k; # fails on linting
 
   postPatch = ''
     sed -i 's#^_mystem_info = .*#_mystem_info = ["${mystem}/bin", "${mystem}/bin/mystem"]#' pymystem3/constants.py