hgwebdir: read 'web.template' untrusted stable

hgwebdir: read 'web.template' untrusted

The 'hgweb_mod.py' version of this read it untrusted. For consistency we align
the two versions of this code.

--- a/mercurial/hgweb/hgwebdir_mod.py	Mon Sep 11 15:59:18 2017 -0700
+++ b/mercurial/hgweb/hgwebdir_mod.py	Fri Sep 15 18:57:50 2017 +0200
@@ -173,7 +173,8 @@
         encoding.encoding = self.ui.config('web', 'encoding',
                                            encoding.encoding)
         self.style = self.ui.config('web', 'style', 'paper')
-        self.templatepath = self.ui.config('web', 'templates', None)
+        self.templatepath = self.ui.config('web', 'templates', None,
+                                           untrusted=False)
         self.stripecount = self.ui.config('web', 'stripes', 1)
         if self.stripecount:
             self.stripecount = int(self.stripecount)