Fix endpoint in missing copyright template

Author: oorestisime

debsources/app/copyright/templates/copyright/missing_copyright.html

@@ -17,6 +17,6 @@ <h2>{{ self.title() }}</h2>
 </ul>
 <a href="{{ url_for('sources.source', path_to=(package +'/'+version+'/debian/copyright'))}}">View raw copyright file</a>
 </p> 
-<a href="{{ url_for('.license', path_to=(package +'/'+version))}}">Go back to the license page</a>
+<a href="{{ url_for('.license', packagename=package, version=version))}}">Go back to the license page</a>
 
 {% endblock %}