[MERGE] forward port of branch saas-3 up to 685fa26

diff --cc addons/web/controllers/main.py
index 0d5a4c0,b59e01b..6f178a4
--- 1/addons/web/controllers/main.py
--- 2/addons/web/controllers/main.py
+++ b/addons/web/controllers/main.py
@@@ -116,10 -148,12 +116,10 @@@ def ensure_db(redirect='/web/database/s
              url_redirect += '?' + r.query_string
          response = werkzeug.utils.redirect(url_redirect, 302)
          request.session.db = db
 -        response = r.app.get_response(r, response, explicit_session=False)
 -        werkzeug.exceptions.abort(response)
 -        return
 +        abort_and_redirect(url_redirect)
  
      # if db not provided, use the session one
-     if not db and http.db_filter([request.session.db]):
+     if not db and request.session.db and http.db_filter([request.session.db]):
          db = request.session.db
  
      # if no database provided and no database in session, use monodb