Hello again,

I investigated against various sources at gnu.org.
The bug exists at least in versions 8.5 to 8.9, and was corrected in
version 8.10, probably by chance during implementation of output formatting
extensions.

Hence the problem comes from debian-squeeze using an old release, and this
issue can be closed, as far as I am concerned.

Thanks for taking the time to test it anyway.

Jean-Pierre