RFR: git-sync: use ref names instead of hashes

[Robin Westberg]

On Fri, 7 Feb 2020 07:19:37 GMT, Erik Helin <ehelin at openjdk.org> wrote:

> Hi all,
> 
> please review this small patch that makes `git sync` avoid using SHA-1 hashes
> when executing `git fetch`. There was nothing wrong with this approach, but
> older `git` clients have problems when the ref to fetch is a SHA-1 hash. There
> is no drawback in using the ref name instead, it only increases compatibility
> with older `git` clients.
> 
> Thanks,
> Erik

Looks good!

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Marked as reviewed by rwestberg (Reviewer).

PR: https://git.openjdk.java.net/skara/pull/408