it sometimes happens that one forgets to add `.run().ok()` to a command,
leading to things not actually being tested, potentially even slipping
though code reviews!
This commit adds a check at fixture teardown time, checking that all
commands have been run. Sadly, due to when this check happens, we cannot
add a test checking for this behavior
Change-Id: If3df2c20c267b9f03ae0ca099b77c57e2310f335
rootile
6b9a121637