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/test/test_exceptions.py b/Lib/test/test_exceptions.py
index d2a2191..c405ac9 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -253,6 +253,12 @@
                                            'ordinal not in range'),
                  'encoding' : 'ascii', 'object' : 'a',
                  'start' : 0, 'reason' : 'ordinal not in range'}),
+            (UnicodeDecodeError, ('ascii', buffer(b'\xff'), 0, 1,
+                                  'ordinal not in range'),
+                {'args' : ('ascii', buffer(b'\xff'), 0, 1,
+                                           'ordinal not in range'),
+                 'encoding' : 'ascii', 'object' : b'\xff',
+                 'start' : 0, 'reason' : 'ordinal not in range'}),
             (UnicodeDecodeError, ('ascii', b'\xff', 0, 1,
                                   'ordinal not in range'),
                 {'args' : ('ascii', b'\xff', 0, 1,
@@ -278,7 +284,7 @@
             try:
                 e = exc(*args)
             except:
-                print("\nexc=%r, args=%r" % (exc, args))
+                print("\nexc=%r, args=%r" % (exc, args), file=sys.stderr)
                 raise
             else:
                 # Verify module name