Changing directories doesn't work well for multithreaded environments

[JacobEvelyn]

We're using UnixUtils.zip with local path names in Sidekiq. As far as we can tell, the chdir calls in UnixUtils are changing the working directory for the entire process, which impacts other Sidekiq threads. We're changing our code to use absolute paths everywhere, but it would probably still be good if UnixUtils didn't change the process' current working directory.