Bug#852475: autopkgtest: apt-get install needs automatic conffile handling

[Martin Pitt]

Hey Barry,

Barry Warsaw [2017-01-24 14:49 -0500]:
> Let's say one of your autopkgtest dependencies (perhaps recursively)
> needs to update a configuration file, i.e. via a conffile.  E.g. when
> running the autopkgtests for aptdaemon in an Ubuntu Zesty chroot, the
> netbase package wants to be installed, and this has conffiles for
> /etc/{protocols,rpc,services}.

Ah, sbuild usually copies that from the host system
(/etc/schroot/default/nssdatabases), so indeed this tends to cause conffile
conflicts.

> It would be better I think when setting up the testbed, to pass to the 
> `apt-get install` command an additional option: 
> - -o Dpkg::Options::="--force-confnew" so that the prompt is bypassed
> and the dependency can be installed.

Agreed. As a matter of fact, --apt-update is already doing that, but
lib/adt_testbed.py's install_apt() is missing it.

Thanks!

Martin