Merging the py3k-pep3137 branch back into the py3k branch.
No detailed change log; just check out the change log for the py3k-pep3137
branch.  The most obvious changes:

  - str8 renamed to bytes (PyString at the C level);
  - bytes renamed to buffer (PyBytes at the C level);
  - PyString and PyUnicode are no longer compatible.

I.e. we now have an immutable bytes type and a mutable bytes type.

The behavior of PyString was modified quite a bit, to make it more
bytes-like.  Some changes are still on the to-do list.
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 4864d97..aef8f94 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -30,13 +30,12 @@
 """
 
 __version__ = "$Revision$"
-# $Source$
 
 version     = "0.9.0"
-__author__  = "Lars Gust\xe4bel (lars@gustaebel.de)"
+__author__  = "Lars Gust\u00e4bel (lars@gustaebel.de)"
 __date__    = "$Date$"
 __cvsid__   = "$Id$"
-__credits__ = "Gustavo Niemeyer, Niels Gust\xe4bel, Richard Townsend."
+__credits__ = "Gustavo Niemeyer, Niels Gust\u00e4bel, Richard Townsend."
 
 #---------
 # Imports
@@ -223,7 +222,7 @@
             # this could raise OverflowError.
             n = struct.unpack("L", struct.pack("l", n))[0]
 
-        s = b""
+        s = buffer()
         for i in range(digits - 1):
             s.insert(0, n & 0o377)
             n >>= 8