hgweb: construct static URL like hgweb does

hgwebdir has a bit of code for constructing URLs. This reinvents wheels
from our parsedrequest instance. And sometimes the behavior varies
from what hgweb does. We'll want to converge that behavior.

This commit changes hgwebdir so its staticurl template keyword
is constructed the same way as hgweb's. There's probably room
to factor this into a shared function. But let's solve the
problem of divergence first.

Differential Revision: https://phab.mercurial-scm.org/D2817

mercurial/hgweb/hgwebdir_mod.py

@@ -542,7 +542,8 b' class hgwebdir(object):'
         sessionvars = webutil.sessionvars(vars, r'?')
         logourl = config('web', 'logourl')
         logoimg = config('web', 'logoimg')
-        staticurl = config('web', 'staticurl') or url + 'static/'
+        staticurl = (config('web', 'staticurl')
+                     or wsgireq.req.apppath + '/static/')
         if not staticurl.endswith('/'):
             staticurl += '/'