All right, this one was solved through some search-fu and interactive discussions on IRC. I am placing it here as a permanent record.
The use case for this one was that someone got themselves a debian net-install, and added #! to their sources list to crunchbangify their own debian, I suppose.
deb http://packages.crunchbang/waldorf waldorf main
This in itself is not sufficient. Because, on running
it produces a GPG error:
W: GPG error: http://packages.crunchbang.org waldorf Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9B7C8627EDFD12C1
So, it looks like one also needs to add a public key! Without it the packages won't get added or installed.
So, how to do it?
wget http://packages.crunchbang.org/waldorf-dev/crunchbang.key \ && apt-key add crunchbang.key
And that's it. That will sort you out.
Thanks for sharing.
I just tried a netinstall myself and struggled with this issue, ended up just installing the Waldorf image anyway.