More reverting of r63675 per the mailing list discussions.  This restores
occurances of PyBytes_ in the code to their original PyString_ names.  The
bytesobject.c file will be renamed back to stringobject.c in a future checkin.
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 3adf0e2..3443b42 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -1207,9 +1207,9 @@
 	 * is expensive, don't unless they're actually used.
 	 */
 	totalnew = format_len + 1;	/* realistic if no %z/%Z/%f */
-	newfmt = PyBytes_FromStringAndSize(NULL, totalnew);
+	newfmt = PyString_FromStringAndSize(NULL, totalnew);
 	if (newfmt == NULL) goto Done;
-	pnew = PyBytes_AsString(newfmt);
+	pnew = PyString_AsString(newfmt);
 	usednew = 0;
 
 	pin = format;