Page not found when the user needs to authorize a request token when drupal is in a subdirectory

I am getting a 404 page when I login to authorize a request token if the site is in a sub-directory.

For example my site is hosted here:
https://example.com/conference/

If the user needs to login to authorize a token the user is redirected here:
https://example.com/conference/user/login?destination=/conference/oauth/...

The problem is that the destination variable is including the sub-directory because we are are using url() to generate the destination url within drupal_goto().

I propose we update this to use http_build_query() instead.

If the user doesn't need to login, the redirection works fine.