--- a/hgext/extdiff.py	Thu Nov 29 09:13:13 2018 +0000
+++ b/hgext/extdiff.py	Tue Dec 04 17:13:01 2018 -0500
@@ -430,6 +430,7 @@
             if args:
                 cmdline += ' ' + args
         command(cmd, extdiffopts[:], _('hg %s [OPTION]... [FILE]...') % cmd,
+                helpcategory=command.CATEGORY_FILE_CONTENTS,
                 inferrepo=True)(savedcmd(path, cmdline))
 
 # tell hggettext to extract docstrings from these functions: