Do not overwrite motd attribute of hgwebdir instances on refresh.

This allows using
application = hgwebdir(...)
application.motd = (string or object with __str__ method)
in WSGI (like it is possible in CGI).

Changed web.motd in the config file is still read with this, because
hgwebdir.templater.motd() does not store the config value.

mercurial/hgweb/hgwebdir_mod.py

@@ -48,6 +48,7 b' class hgwebdir(object):'
         self.conf = conf
         self.baseui = baseui
         self.lastrefresh = 0
+        self.motd = None
         self.refresh()
 
     def refresh(self):
@@ -72,7 +73,6 b' class hgwebdir(object):'
 
         encoding.encoding = self.ui.config('web', 'encoding',
                                            encoding.encoding)
-        self.motd = self.ui.config('web', 'motd')
         self.style = self.ui.config('web', 'style', 'paper')
         self.stripecount = self.ui.config('web', 'stripes', 1)
         if self.stripecount: