Add patch to "warrant" python package with overlay

[Christopher Williamson]

Hi all!

I'm having problems getting a patch applied using an overlay for the "warrant" python package.

A patch is now in the package on GitHub but this hasn't trickled through to the unstable channel yet so trying to get this to build in the meantime.

I'm using an overlay config:

self: super:

rec {
  python = super.python.override {
    packageOverrides = python-self: python-super: {
      warrant = python-super.warrant.overrideAttrs ( oldAttrs: {
        patches = oldAttrs ++ [ ./fix-pip10-compat.patch ];
      });
    };
  };
}

Sadly this patch never seems to actually get applied during the build - this can be verified by attempting to install the home-assistant package which fails even with this overlay in place.

I have tried variants of python, python3, python36, etc. but sadly none of these options worked.

If anyone can help with this one I'd really appreciate it. I have tried to "RTFM" which has led me to the above code (examples being https://nixos.org/releases/tmp/release-nixos-unstable-small/nixos-18.03pre114662.a46f206271/unpack/nixos-18.03pre114662.a46f206271/doc/languages-frameworks/python.md, etc.) but sadly haven't been able to find a working solution.