This was already corrected by r61540, and will be released with 2.5.3
and 2.6.2.

BUT -- fchown() was not modified. patch is similar to r61540, but I
don't know how to test:

Index: posixmodule.c
===================================================================
--- posixmodule.c	(revision 67068)
+++ posixmodule.c	(working copy)
@@ -1902,9 +1902,10 @@
 static PyObject *
 posix_fchown(PyObject *self, PyObject *args)
 {
-	int fd, uid, gid;
+	int fd;
+	long uid, gid;
 	int res;
-	if (!PyArg_ParseTuple(args, "iii:chown", &fd, &uid, &gid))
+	if (!PyArg_ParseTuple(args, "ill:fchown", &fd, &uid, &gid))
 		return NULL;
 	Py_BEGIN_ALLOW_THREADS
 	res = fchown(fd, (uid_t) uid, (gid_t) gid);