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/uuid.py b/Lib/uuid.py
index 74d4a7a..06115c7 100644
--- a/Lib/uuid.py
+++ b/Lib/uuid.py
@@ -234,7 +234,7 @@
 
     @property
     def bytes(self):
-        bytes = b''
+        bytes = buffer()
         for shift in range(0, 128, 8):
             bytes.insert(0, (self.int >> shift) & 0xff)
         return bytes
@@ -548,7 +548,7 @@
         return UUID(bytes=os.urandom(16), version=4)
     except:
         import random
-        bytes = [chr(random.randrange(256)) for i in range(16)]
+        bytes = bytes_(random.randrange(256) for i in range(16))
         return UUID(bytes=bytes, version=4)
 
 def uuid5(namespace, name):