[FIX] /web always save the provided db in session

guessed_db is only computed by the /web controller, so even if the provided db
match the guessed_db we should save it in the http session. Because all rpc
call made before the authentication wont compute the guessed_db, so the
request.db will be wrong for those calls.

bzr revid: al@openerp.com-20131110010411-s7ermjwmfbile1ix

addons/web/controllers/main.py

@@ -553,7 +553,7 @@ class Home(http.Controller):
         if db is None and guessed_db is not None:
             return redirect(guessed_db)
 
-        if db is not None and db != guessed_db:
+        if db is not None and db != request.session.db:
             request.session.logout()
             request.session.db = db
             guessed_db = db