Fix infinite loop issue

[hoelzro]

This addresses GH #481

I don't know how well this will work on Windows, if at all. Something like http://msdn.microsoft.com/en-us/library/aa364953.aspx might provide useful for platform compatability.

[petdance]

@fabioperez What does "Up" mean?

[petdance]

@hoelzro Have you done any performance testing on this? I fear what two stat calls will do.