ui: add environ property to access os.environ or wsgirequest.environ

The property returns os.environ by default, and is propagated by ui.copy.
During hgweb processing, ui.environ is set to the proper WSGI-request
environment, as contained in wsgirequest.environ. For CGI, this is the
same as os.environ.

The property is meant to be read-only, as with os.environ (generally).

mercurial/hgweb/hgweb_mod.py

@@ -54,7 +54,9 b' class hgweb(object):'
         return self.repo.ui.configlist(section, name, default,
                                        untrusted=untrusted)
 
-    def refresh(self):
+    def refresh(self, request=None):
+        if request:
+            self.ui.environ = request.environ
         mtime = get_mtime(self.repo.root)
         if mtime != self.mtime:
             self.mtime = mtime
@@ -80,7 +82,7 b' class hgweb(object):'
 
     def run_wsgi(self, req):
 
-        self.refresh()
+        self.refresh(req)
 
         # work with CGI variables to create coherent structure
         # use SCRIPT_NAME, PATH_INFO and QUERY_STRING as well as our REPO_NAME

mercurial/ui.py

@@ -29,8 +29,11 b' class ui(object):'
             self._ocfg = src._ocfg.copy()
             self._trustusers = src._trustusers.copy()
             self._trustgroups = src._trustgroups.copy()
+            self.environ = src.environ
             self.fixconfig()
         else:
+            # shared read-only environment
+            self.environ = os.environ
             # we always trust global config files
             for f in util.rcpath():
                 self.readconfig(f, trust=True)