diff -r 6e54caaed08d -r 46781c1b5049 mercurial/hgweb/hgwebdir_mod.py
--- a/mercurial/hgweb/hgwebdir_mod.py	Tue Jan 22 17:50:52 2019 -0800
+++ b/mercurial/hgweb/hgwebdir_mod.py	Tue Jan 22 18:07:51 2019 -0800
@@ -510,7 +510,7 @@
         if style == styles[0]:
             vars['style'] = style
 
-        sessionvars = webutil.sessionvars(vars, r'?')
+        sessionvars = webutil.sessionvars(vars, '?')
         logourl = config('web', 'logourl')
         logoimg = config('web', 'logoimg')
         staticurl = (config('web', 'staticurl')