From ab4f2ad832ac2ef924f33816dedb20d3e72e0203 Mon Sep 17 00:00:00 2001
From: Jonathan Ringer <jonringer117@gmail.com>
Date: Sun, 16 Aug 2020 15:38:52 -0700
Subject: [PATCH] python3Packages.yarl: fix build

---
 pkgs/development/python-modules/yarl/default.nix | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/python-modules/yarl/default.nix b/pkgs/development/python-modules/yarl/default.nix
index 325bc710cc22..3ab7fb49c43a 100644
--- a/pkgs/development/python-modules/yarl/default.nix
+++ b/pkgs/development/python-modules/yarl/default.nix
@@ -1,9 +1,12 @@
 { stdenv
+, lib
 , fetchPypi
 , buildPythonPackage
+, pythonOlder
 , multidict
 , pytestrunner
 , pytest
+, typing-extensions
 , idna
 }:
 
@@ -17,7 +20,10 @@ buildPythonPackage rec {
   };
 
   checkInputs = [ pytest pytestrunner ];
-  propagatedBuildInputs = [ multidict idna ];
+  propagatedBuildInputs = [ multidict idna ]
+    ++ lib.optionals (pythonOlder "3.8") [
+      typing-extensions
+    ];
 
   meta = with stdenv.lib; {
     description = "Yet another URL library";