diff --git a/contrib/examples/fix.hgrc b/contrib/examples/fix.hgrc
--- a/contrib/examples/fix.hgrc
+++ b/contrib/examples/fix.hgrc
@@ -4,3 +4,7 @@
 
 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
+# black:pattern = set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**"