If you want to easily test a submitted pull-request, check this tool that I found while reading a discussion on GitHubGist about how to Checkout github pull requests locally.
For instance, it will let you do things like,
$ git pr
$ git pr list closed # not shown by default
$ git pr show 7 # also includes comments
$ git pr patch 7 # can be piped to colordiff if you like colors
$ git pr checkout 7 # create upstream tracking branch pr/7
$ git pr help
$ git pr login # Get access token for commands below
$ git pr close 7
$ git pr open 7
$ git pr comment 7 'This is good stuff!'
Some commands require a valid login, and open and close will not work if the pull request has been merged. For more information, rtfm.