A helpful tip when merging pull requests from outside contributors: use hub for convenience.
https://github.com/defunkt/hub
Follow the standalone instructions, and note the section on Windows if you’re using Git Bash. Among other things, it makes it easy to checkout someone’s pull request directly, without worrying about adding and fetching remote URLs yourself:
hub checkout https://github.com/AnalyticalGraphicsInc/cesium/pull/702
It does lots of other GitHub-oriented things too, such as transmogrifying an issue into a pull request.