gzip unusable on Woody + updates

[Daniel Bonniot <Daniel.Bonniot@inria.fr>]

Hi,

I recently updated a woody machine with security updates. Notably libc6 
is now 2.2.5-11.5.
gzip became unusable. Typing a simple:
$ /bin/gzip
gzip: -b operand is not an integer
usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
$  /bin/gzip /usr/share/doc/zsh/BUGS.gz
gzip: -b operand is not an integer
usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]

I get the same error message "gzip: -b operand is not an integer" 
burried when trying to install new package with apt, since they need 
gunzip'ing.

What is going on?

Daniel

[ please CC: me ]