login event

I've set up a rule to fire on the event "User has logged in," but it doesn't get triggered when I authenticate with Shibboleth (shib_auth module). It does when I login as a native Drupal user or even LDAP user (ldap module). This is for a Drupal 7 site.

What is the actual hook/method that "User has logged in" depends on? The shib_auth module calls user_external_login_register which then calls user_login_submit, so I'm not sure what's getting bypassed. Would the best solution be a custom event "Shibboleth user has logged in," or might this be considered a bug in the shibboleth module?

In my installation the users login with Shibboleth [1], but the rule [2] I've set up to be executed on "User has logged in" event, isn't executed.

On the other hand, when I login as administrator through the normal Drupal way, the rule is executed.

Does this mean that the external login event isn't handled at all?

Is there a way to overcome this?

[1] http://drupal.org/project/shib_auth
[2] http://drupal.org/project/rules