I was so excited when I saw this post. Then I realized it's another 'too early' post claiming the tag == release. It's not released until it happens on the PHP site. This is just a tag in the repo. Sure, it likely won't change now, but it could.
[1] https://twitter.com/official_php/status/669940548128534528
If you tag a commit you better stick to your guns and never change it. You can't just re-tag or re-roll your releases because you found a bug. Bugs happen. Increment your version number, cut/tag a new release, and move on. You will never have a perfect release. Ever.
If you create a php-7.0.0 tag, and you find a bad bug, then make a new tag, either php-7.0.1, or since you might still want to call the release PHP 7.0.0, maybe name it php-7.0.0-bugfix1 or something.