prevent stringio error from opening small files

When running thor download I get the following: https://gist.github.com/nitay/0cbf5ccb2bc611f627e5
After digging I found it's because of this: http://stackoverflow.com/questions/694115/why-does-ruby-open-uris-open-return-a-stringio-in-my-unit-test-but-a-fileio-in