python3Packages.m2r: patch docutils 0.19 compat

pkgs/development/python-modules/m2r/default.nix

@@ -22,6 +22,7 @@ buildPythonPackage rec {
       url = "https://github.com/miyakogi/m2r/commit/58ee9cabdadf5e3deb13037f3052238f0f2bffcd.patch";
       sha256 = "sha256-CN3PWmnk7xsn1wngRHuEWmDTP3HtVNxkFv0xzD2Zjlo=";
     })
+    ./docutils-0.19-compat.patch
   ];
 
   postPatch = ''

pkgs/development/python-modules/m2r/docutils-0.19-compat.patch

@@ -0,0 +1,15 @@
+diff --git a/m2r.py b/m2r.py
+index a4e43c2..fb9e588 100644
+--- a/m2r.py
++++ b/m2r.py
+@@ -10,8 +10,8 @@ from argparse import ArgumentParser, Namespace
+ 
+ from docutils import statemachine, nodes, io, utils
+ from docutils.parsers import rst
+-from docutils.core import ErrorString
+-from docutils.utils import SafeString, column_width
++from docutils.utils.error_reporting import ErrorString, SafeString
++from docutils.utils import column_width
+ import mistune
+ 
+ if sys.version_info < (3, ):