Fix handling of resolv.conf in the chroot #134
Merged
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We have some logic in place that backs-up the resolv.conf in the chroot, puts the host one in place for package installation and then restores the original resolv.conf so that we don't leak the host config into the images. Sadly, it seems that debootstrap basically copies the resolv.conf from the host system into the chroot it generates. Looking into what live-build was doing, it seems that live-build was always truncating the resolv.conf that we were getting from debootstrap, so let's do the same.
While checking what live-build was doing, I also noticed a nifty conditional that checks if during package installation resolv.conf wasn't substituted with a symlink (example has been given of systemd-resolved or resolvconf), and making sure we leave the new resolv.conf symlink in place. So I added it here as well.
All changes come with testing. Had to add a new test suite for the helper functions.