Bug#610753: debootstrap: use apt trusted keys with --keyring by default

[dave b <db.pub.mail@gmail.com>]

> The problem with this idea is that debootstrap can be used:
>
> - to bootstrap on another distribution, which won't have that keyring
> - to bootstrap one Debian or derivative on another, so that keyring
>  will be present but not have the right keys in it
> - to bootstrap unstable on stable, so the keyring may have only old
>  keys in it, not the current key used to sign unstable
>  (I haven't checked if/when that occurs.)
> - to bootstrap during installation, from a CD, in which case there
>  is no available keyring at that point, and the media is trusted
>
> Especially the first 3 cases seem hard to reconcile with checking
> signatures by default.
>

Well yes this would be a change from the current behaviour.
If you don't have the key in the keyring then debootstrap will not be
able to check the release files and will not continue.
If the key is in the keyring then debootstrap will continue.

Perhaps to complement --keyring, --key could also exist. (making it
slightly easier to work with).

with
1. - the user will now have to put the required key into the keyring
(by default)

2. while this may be possible, it probably is wise if the user fetches
the key (like in 2)

3. Hum, isn't there cd key ?(you could check the iso is ok) / how does
the D-I handle it ?

With 3. perhaps a --no-keyring option could be used?