diff -r d770a08ee9d9 -r 633c635a790a mercurial/help.py
--- a/mercurial/help.py	Sun May 28 15:43:06 2017 -0400
+++ b/mercurial/help.py	Sun May 28 15:51:07 2017 -0400
@@ -266,7 +266,8 @@
             continue
         text = gettext(text)
         if dedent:
-            text = textwrap.dedent(text)
+            # Abuse latin1 to use textwrap.dedent() on bytes.
+            text = textwrap.dedent(text.decode('latin1')).encode('latin1')
         lines = text.splitlines()
         doclines = [(lines[0])]
         for l in lines[1:]: