I noticed in the static deltas tests, there were some tests that
should have been under `-o pipefail` to ensure we properly propagate
errors.
There were a few places where we were referencing undefined variables.
Overall, this is clearly a good idea IMO.
Eliminates the need for constantly passing --sysroot=sysroot, but
also makes ostree place remote configs for sysroot/ostree/repo in
sysroot/etc/ostree/remotes.d where they should have been all along.