better request.requires_https, thanks Yarin and Niphlod

gluon/globals.py

@@ -128,6 +128,7 @@ class Request(Storage):
         and secure the session.
         """
         if not global_settings.cronjob and not self.is_https:
+            session.forget()
             redirect(URL(scheme='https', args=self.args, vars=self.vars))
 
         current.session.secure()