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/Modules/dbmmodule.c b/Modules/dbmmodule.c
index 5660882..6b05fad 100644
--- a/Modules/dbmmodule.c
+++ b/Modules/dbmmodule.c
@@ -219,14 +219,14 @@
 		if (arg == NULL)
 			return -1;
 	}
-	if (!PyBytes_Check(arg)) {
+	if (!PyString_Check(arg)) {
 		PyErr_Format(PyExc_TypeError,
 			     "dbm key must be string, not %.100s",
 			     arg->ob_type->tp_name);
 		return -1;
 	}
-	key.dptr = PyBytes_AS_STRING(arg);
-	key.dsize = PyBytes_GET_SIZE(arg);
+	key.dptr = PyString_AS_STRING(arg);
+	key.dsize = PyString_GET_SIZE(arg);
 	val = dbm_fetch(dp->di_dbm, key);
 	return val.dptr != NULL;
 }