Redirect results in strange URL

When I redirect a user after login using an event handler, the request.response.redirect(url + user_dir) results in the resulting URL to look like http://localhost:8080/Plone/users/143930354440126#_=_. What the hell is up with that #_=_ on the end of the URL..? Is there a way to rewrite this or lock the redirect path?

In this case the variable url is http://localhost:8080/Plone and the variable user_dir is users/143930354440126.

I'm not sure where the #_=_ is coming from though...