Document key issue

[jamesbennet]

In order to get an Ubuntu based buildd to build for Debian sid I went to do:

sudo sbuild-createchroot unstable /srv/chroot/unstable http://ftp.uk.debian.org/debian

But i got:

jamesb@newpc:~/pybit$ sudo sbuild-createchroot unstable /srv/chroot/unstable http://ftp.uk.debian.org/debian
I: SUITE: unstable
I: TARGET: /srv/chroot/unstable
I: MIRROR: http://ftp.uk.debian.org/debian
I: Running debootstrap --arch=i386 --variant=buildd --verbose --include=fakeroot,build-essential --components=main --keyring=/etc/apt/trusted.gpg --resolve-deps unstable /srv/chroot/unstable http://ftp.uk.debian.org/debian
I: Retrieving InRelease
I: Checking Release signature
E: Release signed by unknown key (key id AED4B06F473041FA)
E: Error running debootstrap at /usr/sbin/sbuild-createchroot line 200.

This seems to be due to: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=614029

Doing this made it work:

sudo gpg --no-default-keyring --keyring /etc/apt/trusted.gpg --recv-keys AED4B06F473041FA

This seems to be as the debian-archive-keyring package on Ubuntu puts them in the wrong place (/etc/apt/trusted.gpg.d) where they cant be found.

This should be documented by someone who knows how/why it works.