nixpkgs/pkgs/development/python-modules/contextvars/immutables_version.patch

--- ./setup.py	2018-07-30 15:40:14.000000000 +0000
+++ ./setup.py	2019-02-12 18:33:24.984430303 +0000
@@ -17,7 +17,7 @@
     packages=['contextvars'],
     provides=['contextvars'],
     install_requires=[
-        'immutables==0.6',
+        'immutables>=0.6',
     ],
     license='Apache License, Version 2.0',
     classifiers=[