Feature: add "comment on line in diff"

[jamesarosen]

I'd love to use this to help me with my code reviews.

1: pipe the diff into TextMate:

$ git diff HEAD~5..HEAD | mate

2: select "Git -> Comment on line from diff"

3: GitHub.Bundle parses the diff file for the closest file marker above the current line and calculates an offset from there to get the line number

4: GitHub.Bundle runs git blame on the file and calculated line

1. GitHub.Bundle generates a URL for the commit/file/line and opens it in the browser.