oauth-php not taking account of proxy setting

There is an issue getting LTI working between Moodle and Mahara in the oauth-php library as it doesn't take Mahara's sslproxy configuration into consideration when generating the URI for $base_string

I'd like to propose a patch for Mahara that looks something like a change on line 92 of htdocs/webservice/rest/locallib.php
From this...

 $this->oauth_server = new OAuthServer();

To this...

 // Instantiating OAuthServer() with get_full_script_path() ensures that
 // the locally generated signature will contain a URI using the correct
 // protocol if this server is behind an sslproxy.
 // Otherwise OAuthServer() determines the protocol based only on a
 // check for $_SERVER['HTTPS'] and signature verification will fail.
 $this->oauth_server = new OAuthServer(get_full_script_path());

Essentially the OAuthRequest() class assumes that because the web container is not using SSL directly then the request URI should be prefixed with http:// rather than https://...

$proto = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') ? 'https' : 'http';

But it seems OK to instantiate OAuthServer() with a $uri to bypass this, so that could be done in webservice_rest_server::parse_request() rather than having to patch oauth-php directly, I think get_full_script_path() seems OK to use for this.