report full file size when offset is used

lib/uristream.js

@@ -99,7 +99,7 @@ function setupHttp(uri, options, dst) {
         return failOrRetry(new Error('Bad server response code: '+res.statusCode), res.statusCode >= 500 && res.statusCode !== 501);
 
       if (res.headers['content-length']) size = parseInt(res.headers['content-length'], 10);
-      var filesize = (size >= 0) ? start + size - offset : -1;
+      var filesize = (size >= 0) ? start + size : -1;
 
       // transparently handle gzip responses
       var stream = res;