can.route.url creates invalid url

When building a url using

1. can.route.url( {controller: 'user', action: 'login', returnUrl: returnPage}, false )

can force-encodes the whole url. Whereas one would expect the url to be:

1. user/login&returnUrl=encodedUrl

instead you get an invalid url:

1. &user%2Flogin=&returnUrl=encodedUrl

Can this be overcome somehow?