RFR: 205: git-pr: allow configurable default action

[Robin Westberg]

On Mon, 16 Dec 2019 10:35:08 GMT, Erik Helin <ehelin at openjdk.org> wrote:

> Hi all,
> 
> please review this small patch that makes the default action of `git pr`
> configurable.
> 
> Thanks,
> Erik
> 
> ## Testing
> - [x] Manual testing of `git pr` with and without a default action

Looks good!

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Marked as reviewed by rwestberg (Reviewer).

PR: https://git.openjdk.java.net/skara/pull/332