Ahh.. probably another bug. It might be a good idea to add working directory as a parameter to `Proc` constructor so that users would be forced to explicitly set it every time a `Proc` is created, this might help avoid this kind of bug since it would force user to think about process' working directory. I just checked usages of `Proc` class and currently  we're always setting working directory just after the `Proc` object is constructed.