Dear Aurelien, dear all, for unrelated reasons I had to reinstall my system and now everything works fine with the latest libc6. I suppose there was some sort of horrible conflict somewhere. Hopefully it won't be reproducible anywhere else.
As far as I'm concerned, case closed. -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org