Update layers.py

Author: dmp42

docker_registry/lib/layers.py

@@ -59,7 +59,7 @@ def _proxy(self, method, *args, **kwargs):
         if not self.compressed:
             return getattr(self._fp, method)(*args, **kwargs)
         if self.compressed:
-            previous = self._sp.tell()
+            previous = self._fp.tell()
             try:
                 return getattr(super(Archive, self), method)(*args, **kwargs)
             except lzma._lzma.LZMAError: