debconf hangs during sarge/etch install

[Adrian Bridgett <adrian@smop.co.uk>]

Hi guys, 

I've got an automatic install (PXE, preseed) working nicely on sarge,
however I need to use a later kernel (network card and SATA controller).

So I've used Kenshi Muto's excellent backports and things are _mostly_
working.  However in the preseed/late-command section I install some
extra packages and this is hanging/failing handling the debconf
commands in postinsts (and anywhere else).

Typically I'm seeing messages like this:

"/tmp/ssh.config.307932: line 42: 3: Bad file descriptor"

I've tried various things:
a) upgrading debconf (to 1.4.72, then 1.5.0)
b) setting LANG to C, en_GB.UTF-8 (bug 355251 - fixed in debconf 1.5.0)
c) DEBIAN_FRONTEND=noninteractive
d) removing /etc/apt/apt.conf.d/70debconf
e) removing a high level redirect I had (to save the output of the
scripts)

I thought I'd ask the experts instead of stabbing around in the dark.
This used to work okay, but used to be a base-config/late_command
(which doesn't exist anymore).

I can reproduce this at the command line by waiting for the hang, then
killing off the "sh /tmp/ssh.config.307932 configure" command (my
script then does a sleep so I can debug the failure).

If I then set both  DEBIAN_HAS_FRONTEND=1 and DEBCONF_REDIR=1 then I
see the same behaviour.  If I unset both, ssh installs fine.

I realise it won't be inheriting the parent FDs, but hopefully it's a
useful clue.

Many thanks,

Adrian