Hi,
the 'url' attribute is a special one - it will be modified during xml loading.
When the value of the url attribute in the xml is a relative one, then the relative path of the xml will be added.
See here:
http://krpano.com/docu/xml/#url-notes
The resolving of the %$var% happens later on the loading request, but at this point the path was already added.
I will consider adding a special handling for the next releases here - when the value of $var will be an absolute path, then the part before that variable will be stripped away.
Best regards,
Klaus