Will/jenkins diff cover

[wedaly]

This PR updates diff-cover version 0.1.1, which uses git diff origin/master...HEAD instead of git diff master...HEAD. Since the local master branch is not always current in Jenkins, this ensures that we're comparing to the most recent version of master.

Suggested reviewers: @jzoldak @cpennington

[cpennington]

Git doesn't treat revisions differently than branches, so I'm not sure why creating a local branch would matter in this case. In particular, on my machine, git diff origin/master...HEAD with a particular revision checked out behaves the same as git diff origin/master...HEAD when the branch is checked out.

[cpennington]

Can you actually just do a rebase and remove both eed66 and c7af1 from the history entirely? (Assuming that it works w/o them)

[wedaly]

@cpennington After further experimentation, I agree with you. The change was in response to some strangeness I was seeing in Jenkins (lots of extra commits showing up in git diff origin/master...HEAD)

I want to get this merged, then watch the diff coverage HTML report to see if there are edge cases with git diff that are not being handled correctly.

[cpennington]

👍, shipit

[jzoldak]

👍