PHP 7.0.15 RC1 was just released and can be downloaded from:

https://downloads.php.net/~ab/

The Windows binaries are available at

http://windows.php.net/qa/

This release contains a number of bugfixes.
For the list of bugfixes that you can target in your testing, please refer
to the NEWS file:

https://github.com/php/php-src/blob/php-7.0.15RC1/NEWS

Please test it carefully, and report any bugs in the bug system.

The stable release is planned for January 19th, if no critical issues will
be discovered in the RC.