diff -r 3e6b36ba16ac -r f12de15c5711 mercurial/configitems.py
--- a/mercurial/configitems.py	Wed Oct 11 04:15:08 2017 +0200
+++ b/mercurial/configitems.py	Wed Oct 11 04:15:24 2017 +0200
@@ -736,6 +736,9 @@
 coreconfigitem('web', 'deny_push',
     default=list,
 )
+coreconfigitem('web', 'guessmime',
+    default=False,
+)
 coreconfigitem('web', 'accesslog',
     default='-',
 )