fixed Issue 1539:user_groups are not updated during and after impersonation, thanks kmouts

VERSION

@@ -1 +1 @@
-Version 2.5.1-stable+timestamp.2013.06.17.04.40.23
+Version 2.5.1-stable+timestamp.2013.06.17.08.04.19

gluon/tools.py

@@ -2924,6 +2924,7 @@ class Auth(object):
             auth.user.update(
                 table_user._filter_fields(user, True))
             self.user = auth.user
+            self.update_groups()
             onaccept = self.settings.login_onaccept
             log = self.messages.impersonate_log
             self.log_event(log, dict(id=current_id, other_id=auth.user.id))
@@ -2938,6 +2939,7 @@ class Auth(object):
                 session.clear()
                 session.update(cPickle.loads(auth.impersonator))
                 self.user = session.auth.user
+                self.update_groups()
             return None
         if requested_id is DEFAULT and not request.post_vars:
             return SQLFORM.factory(Field('user_id', 'integer'))