Redirection to node view after node creation generates messed up URL

I have a test site at http://localhost/p/pui/.

After I create a purchased node, paypernode is redirecting me to http://localhost/p/pui//p/pui/node/IDNUMBER.

It is the code at line 315 in paypernode.module that's doing a redirect like this:

$form_state['redirect']=url('node/'.$node->nid);

It shouldn't be using the url() function. I removed it and now it correctly redirects me to http://localhost/p/pui/node/IDNUMBER

This is more like the usage in the reference: Forms API reference: redirect