Bug#279590: base-config: http/proxy fails to preseed

[Christian Perrier <bubulle@debian.org>]

Quoting Joey Hess (joeyh@debian.org):
> Paul Telford wrote:
> > Tested using the netinst iso from
> > http://cdimage.debian.org/pub/cdimage-testing/sid_d-i/i386/20041102/
> > 
> > Primary install source is on my local subnet.
> 
> In that case you're hitting some other bug, it should have set up the
> proxy for your main apt source and continued to use it for security.

Hmm, well, that case (netinst CD then security download failing in 2nd
stage) is the exact case for which I reported #255651...and proposed
the fix I sent for it.

This fix is not easy to test because the situation mostly shows up for
netinst CDs...which always use sarge base-config....

Testing my fix needs to manually change apt-setup with the fix before
running 2nd stage.....or manually install sid's base-config at the end
of 1st stage.

After some thinking, I imagine that my fix for 255651 may have other
consequences:
		# Ask about a proxy if no proxy is yet defined.
		if [ "$URI" = "http" ] && [ -z "$http_proxy" ]; then
			if [ ! -e "$APTETC/apt.conf" ] || \
			   ! grep -iq 'Acquire::http::Proxy' $APTETC/apt.conf; then
				db_input high mirror/http/proxy || true
				.../...


With that, if the earlier stages have already prompted the user for a
proxy and the user did not enter anything because she doesn't need
one...then she will be prompted again for a proxy. In short, netboot
and businesscard installs are likely to prompt twice for a proxy.

A better fix would be:

if URI is http and http_proxy is empty and mirror/http/proxy has not
been seen ; then
  input for proxy
fi