pythonPackages.xlib: fix 'No protocol specified'

Fixes an upstream bug (python-xlib/python-xlib#207). Without this patch,
streamdeck-ui breaks on NixOS systems running GNOME on Xorg.

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

@@ -22,6 +22,10 @@ buildPythonPackage rec {
     sha256 = "155p9xhsk01z9vdml74h07svlqy6gljnx9c6qbydcr14lwghwn06";
   };
 
+  patches = [
+    ./fix-no-protocol-specified.patch
+  ];
+
   nativeBuildInputs = [ setuptools-scm ];
   buildInputs = [ xorg.libX11 ];
   propagatedBuildInputs = [ six ];

pkgs/development/python-modules/xlib/fix-no-protocol-specified.patch

@@ -0,0 +1,13 @@
+diff --git a/Xlib/xauth.py b/Xlib/xauth.py
+index 2ed7dd5..303bd49 100644
+--- a/Xlib/xauth.py
++++ b/Xlib/xauth.py
+@@ -120,6 +120,8 @@ class Xauthority(object):
+         matches = {}
+ 
+         for efam, eaddr, enum, ename, edata in self.entries:
++            if enum == b'' and ename not in matches:
++                enum = num
+             if efam == family and eaddr == address and num == enum:
+                 matches[ename] = edata
+