MT#9905 Make sure piuparts chroot is up2date

The tarball that is used for unpacking doesn't include Sipwise'
apt-key so (dist-)upgrading it fails and the wrong checksums
are used. E.g. our tarball ships an older version of perl-base
than you get with the 7.7 point release nowadays and therefore
we get:

| After purging files have been modified: /usr/share/doc/perl/changelog.Debian.gz owned by: perl-base

as a result. By ensuring that our chroot is properly updated
we can avoid this issue.

To use this feature it requires the patch I provided in
Debian's #767485, I'll provide an according backport on our
infrastructure.

scripts/post_chroot_unpack_sipwise_key.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+echo "** Executing $0 to fix apt-key usage after bootstrapping/unpacking chroot **"
+
+echo "** Running apt-get update to make sure we have up2date package information available **"
+apt-get update
+
+# make sure we can rely on wget being present for checks
+echo "** Installing wget **"
+which wget >/dev/null 2>&1 || apt-get --allow-unauthenticated -y install wget
+
+echo "** Setting up http://deb.sipwise.com/autobuild/680FBA8A.asc for apt-get usage **"
+wget -O - http://deb.sipwise.com/autobuild/680FBA8A.asc | apt-key add -
+
+echo "** Running apt-get update to have a verified Debian repository available **"
+apt-get update

wrapper/piuparts_runner

@@ -53,6 +53,9 @@ case "$distribution" in
     ;;
 esac
 
+# we need wget for apt-key installation via scripts/post_chroot_unpack_sipwise_key.sh
+debootstrap_options="$debootstrap_options --include=wget"
+
 piuparts_cmdline="sudo release=$release SCRIPTSDIR=$PWD/source/scripts/ MIRROR=$mirror distribution=$distribution DEBOOTSTRAP_OPTIONS=$debootstrap_options piuparts_wrapper --mirror=$mirror -i etc/init.d/ngcp-hylafaxplus -i etc/default/ngcp-iaxmodem"
 
 ce_pro_carrier() {