A new test in 8.20 fail because "mount point 'a/b' already traversed" is not emitted

[chroot-i486] root:/usr/src/coreutils-8.20$ uname -r; mount --version
3.4.15
mount from util-linux 2.22.1 (libmount 2.22.0: debug)

[chroot-i486] root:/usr/src/coreutils-8.20$ FORCE_UNSAFE_CONFIGURE=1 ./configure --prefix=/usr --disable-nls --enable-no-install-program=kill,uptime
...
[chroot-i486] root:/usr/src/coreutils-8.20$ make check TESTS=tests/du/bind-mount-dir-cycle.sh
...
FAIL: tests/du/bind-mount-dir-cycle.sh (exit: 1)
...
+ mkdir -p a/b
+ mount --bind a a/b
+ echo a
+ echo 'du: mount point '\''a/b'\'' already traversed'
+ du a
+ sed 's/^[0-9][0-9]*   //' out
+ mv k out
+ compare exp-err err
+ compare_dev_null_ exp-err err
+ test 2 = 2
+ test xexp-err = x/dev/null
+ test xerr = x/dev/null
+ return 2
+ case $? in
+ compare_ exp-err err
+ diff -u exp-err err
--- exp-err     2012-10-25 09:24:00.000000000 +0200
+++ err 2012-10-25 09:24:00.000000000 +0200
@@ -1 +1,6 @@
-du: mount point 'a/b' already traversed
+du: WARNING: Circular directory structure.
+This almost certainly means that you have a corrupted file system.
+NOTIFY YOUR SYSTEM MANAGER.
+The following directory is part of the cycle:
+  'a/b'
+
+ fail=1
+ compare exp out
+ compare_dev_null_ exp out
+ test 2 = 2
+ test xexp = x/dev/null
+ test xout = x/dev/null
+ return 2
+ case $? in
+ compare_ exp out
+ diff -u exp out
+ Exit 1
+ set +e
+ exit 1
+ exit 1
+ remove_tmp_
+ __st=1
+ cleanup_
+ umount a/b

I attached the result of strace -o du-bind-mount-dir-cycle.log -s100 -f du a

Gilles