Pull from GitHub's provided merge ref.
Updated git spec.
small improvements to code for working with fetched merges
Merge pull request #1 from vaneyckt/use-github-pull-request-ref-review

small improvements to code for working with fetched merges
Merge pull request #30 from kmcbride/use-github-pull-request-ref

Pull from GitHub's provided merge ref.
first set of small changes
Merge pull request #1 from vaneyckt/jsandrew-improvements-review

Jsandrew improvements review