See https://github.com/coreos/coreos-assembler/pull/1528 I think we can drop the old cosa reboot APIs after this, though I've already forgotten where else I might have written tests using it.
Follow the precedent set in https://github.com/coreos/rpm-ostree/pull/2106 and rename the directory, to more clearly move away from the "uninstalled" test model. Prep for Rust-based tests.
Colin Walters