Fix for issue #649. 'git branch' unknown '--quiet' option was removed.

[bsalex]

Fix for issue #649

[ljharb]

This was added intentionally. What version of git are you using such that --quiet is not an option? You should be on v2.2.1 or higher due to security issues https://github.com/blog/1938-git-client-vulnerability-announced

[bsalex]

I'm using v1.7.1.
Unfortunately I have no permissions to upgrade it.

[ljharb]

I'd prefer to add an explicit version check so that git isn't auto-selected as an install option when the git version isn't high enough. Still using git v1.7.1 is like still using IE 6, so I don't wish to support it.

[ljharb]

@bsalex Thanks for the PR! The effort is definitely appreciated even when a change doesn't end up landing.

If you'd like to submit a PR that gives a more useful error message, or avoids the git install method when --quiet is not supported, I'd love to accept that.