I'm not sure exactly why, but, _known_hosts is trying to execute /dev/null. As a workaround you can apply the patch below. This fixes only the symptoms so the bug should remain open.
--- /etc/bash_completion.d/ssh.old 2009-05-02 02:12:09.000000000 -0700 +++ /etc/bash_completion.d/ssh 2009-05-02 02:26:20.000000000 -0700 @@ -102,7 +102,7 @@ shift done - [[ "$cur" == */* ]] || _known_hosts -c -a "$optconfigfile" + [[ "$cur" == */* ]] || _known_hosts -c -a "$optconfigfile" 2> /dev/null # This approach is used instead of _filedir to get a space appended # after local file/dir completions, and $nospace retained for others. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org