Backport the nts() function from the trunk. This fixes problems with
the xstar format that puts extra fields inside the space that POSIX
has reserved for the prefix field.
diff --git a/Misc/NEWS b/Misc/NEWS
index e9473dd..0cd7407 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -83,6 +83,8 @@
 Library
 -------
 
+- tarfile.py: Fix reading of xstar archives.
+
 - #2021: Allow tempfile.NamedTemporaryFile to be used in with statements
   by correctly supporting the context management protocol.