Comment 2 for bug 1881977

This was my fault. When I updated Curtin for CentOS 8 I used realpath as its part of coreutils in Xenial+. I forgot that it is a separate package in Trusty and Precise. When Curtin installs GRUB it does so chrooted into the environment being deployed. The Curtin version being used comes from MAAS so we could fix this without touching the Trusty archives.