certifi: Patch to work under Python 2.

certifi being only Python3 breaks a lot of Python 2 packages via the
requests packages. Patch the library to work under Python 2.

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

@@ -1,6 +1,5 @@
 { lib
 , buildPythonPackage
-, isPy27
 , fetchFromGitHub
 , pytestCheckHook
 }:
@@ -9,15 +8,17 @@ buildPythonPackage rec {
   pname = "certifi";
   version = "2021.05.30";
 
-  disabled = isPy27;
-
   src = fetchFromGitHub {
     owner = pname;
     repo = "python-certifi";
     rev = version;
     sha256 = "1i4ljsc47iac6kl1w4w6x0qia08s9z394z9lbyzc05pm7y8a3cmj";
   };
 
+  patches = [
+    ./reenable-python2.diff
+    ./read-file-for-python2.diff
+  ];
   checkInputs = [
     pytestCheckHook
   ];

pkgs/development/python-modules/certifi/read-file-for-python2.diff

@@ -0,0 +1,20 @@
+diff --git a/certifi/core.py b/certifi/core.py
+index 5d2b8cd..3261f82 100644
+--- a/certifi/core.py
++++ b/certifi/core.py
+@@ -45,8 +45,13 @@ except ImportError:
+     # so won't address issues with environments like PyOxidizer that don't set
+     # __file__ on modules.
+     def read_text(_module, _path, encoding="ascii"):
+-        with open(where(), "r", encoding=encoding) as data:
+-            return data.read()
++        try:
++            with open(where(), "r", encoding=encoding) as data:
++                return data.read()
++        except TypeError:
++            # Read under Python2.7
++            with open(where(), "r") as data:
++                return data.read()
+
+     # If we don't have importlib.resources, then we will just do the old logic
+     # of assuming we're on the filesystem and munge the path directly.

pkgs/development/python-modules/certifi/reenable-python2.diff

@@ -0,0 +1,33 @@
+diff --git a/README.rst b/README.rst
+index 182b511..9704bcb 100644
+--- a/README.rst
++++ b/README.rst
+@@ -21,12 +21,12 @@ built-in function::
+     >>> import certifi
+
+     >>> certifi.where()
+-    '/usr/local/lib/python3.7/site-packages/certifi/cacert.pem'
++    '/usr/local/lib/python2.7/site-packages/certifi/cacert.pem'
+
+ Or from the command line::
+
+     $ python -m certifi
+-    /usr/local/lib/python3.7/site-packages/certifi/cacert.pem
++    /usr/local/lib/python2.7/site-packages/certifi/cacert.pem
+
+ Enjoy!
+
+diff --git a/setup.py b/setup.py
+index 69ec098..cadf7ff 100755
+--- a/setup.py
++++ b/setup.py
+@@ -54,6 +54,9 @@ setup(
+         'License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)',
+         'Natural Language :: English',
+         'Programming Language :: Python',
++        'Programming Language :: Python :: 2',
++        'Programming Language :: Python :: 2.6',
++        'Programming Language :: Python :: 2.7',
+         'Programming Language :: Python :: 3',
+         'Programming Language :: Python :: 3.3',
+         'Programming Language :: Python :: 3.4',