--- a/contrib/examples/fix.hgrc	Sat Oct 05 09:58:21 2019 -0400
+++ b/contrib/examples/fix.hgrc	Sun Oct 06 14:13:03 2019 -0700
@@ -5,6 +5,11 @@
 rustfmt:command = rustfmt {rootpath}
 rustfmt:pattern = set:**.rs
 
-# We use black, but currently with https://github.com/psf/black/pull/826 applied.
-# black:command = black --skip-string-normalization
+# We use black, but currently with
+# https://github.com/psf/black/pull/826 applied. For now
+# contrib/grey.py is our fork of black. You need to pip install
+# git+https://github.com/python/black/@d9e71a75ccfefa3d9156a64c03313a0d4ad981e5
+# to have the dependencies for grey.
+#
+# black:command = python3.7 contrib/grey.py --skip-string-normalization
 # black:pattern = set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/**"