Code review comment for lp:~gz/juju-ci-tools/gzip_logs_hang

The code looks fine, but I think the tests should create log files if necessary. We want to assert that gzip -f gets run. And we want a test case for dump_logs, asserting that it doesn't run gzip if there are no logs. Yes, there are no tests for deploy_stack, but I think that needs to change. I've been adding tests for other testless functionality when I change it.