Error "There are problems and -y was used without --force-yes" when deb package installation

[Spring Zhang]

I found the error in apt-get usage sometimes, not just here:

LAVA: (stdout) The following NEW packages will be installed:
LAVA: (stdout) emacsen-common git git-core git-man libasound2-dev liberror-perl libfftw3-3
LAVA: (stdout) libfftw3-dev
LAVA: (stdout) 0 upgraded, 8 newly installed, 0 to remove and 59 not upgraded.
LAVA: (stdout) Need to get 7761 kB of archives.
LAVA: (stdout) After this operation, 17.3 MB of additional disk space will be used.
LAVA: (stdout) WARNING: The following packages cannot be authenticated!
LAVA: (stdout) emacsen-common liberror-perl git-man git git-core libasound2-dev libfftw3-3
LAVA: (stdout) libfftw3-dev
LAVA: (stderr) E: There are problems and -y was used without --force-yes
ERROR: Command 'sudo apt-get install -y git-core libasound2-dev libfftw3-dev gcc' returned non-zero exit status 100

I think it could be better to add the option to the installer.

[Michael Hudson-Doyle (mwhudson)]

I would at least like to understand why this happens before we apply the
blunt hammer that is --force-yes.

[Spring Zhang (qzhang)]

I would at least like to understand why this happens before we apply the
> blunt hammer that is --force-yes.
>
So do I.

[Paul Larson (pwlars)]

https://bugs.launchpad.net/linaro-image-tools/+bug/638384 seems to be related, talked to Danilo and it seems that force-yes is an appropriate thing to do here. After all, this is just for installing packages into the test image that other things depend on. We don't want to have it blocking waiting for users to approve this, which will never happen. In fact, I thought we were already doing force-yes at one time.