--- tarfile-orig.py	2007-04-05 21:39:35.000000000 +0200
+++ tarfile.py	2007-04-06 11:57:27.000000000 +0200
@@ -1044,7 +1044,10 @@
            can be determined, `mode' is overridden by `fileobj's mode.
            `fileobj' is not closed, when TarFile is closed.
         """
-        self.name = os.path.abspath(name)
+        if name is not None:
+            self.name = os.path.abspath(name)
+        else:
+            self.name = name
 
         if len(mode) > 1 or mode not in "raw":
             raise ValueError("mode must be 'r', 'a' or 'w'")