Hello, I've opened https://github.com/php/php-src/pull/770 for patches for bugs #65463, #66036. More details in the PR.
The bug is reproducible on PHP 5.4, 5.5 and 5.6 with and without --enable-zend-signals. Please review, I'm hesitant to merge such a core change without more eyes. Thanks, Keyur.
