Doesn't work with GitHub urls that point at files

[friism]

Examples:

• https://github.com/guardian/gu-who/blob/master/heroku.md
• https://github.com/heroku/node-js-sample/blob/master/README.md

/cc @raulb

[AndersDJohnson]

@friism I'm running some test cases, I see "user" and "repo" working, but not necessarily "branch". Is this your issue? Or did you expect file path parsing also?