Segmentation fault when compiling Phalcon 2.1 on Ubuntu 16.04 for PHP7

When installing Phalcon on fresh Ubuntu 16.04, I'm getting the 'Segmentation fault (core dumped)'.

Note the 16.04 comes with PHP7 by default.

Installing Phalcon with Zephir

# apt-get install php-dev re2c libpcre3-dev
# php -v
PHP 7.0.4-7ubuntu2 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
# git clone https://github.com/phalcon/zephir.git
# cd zephir
# ./install -c
# cd ..
# git clone https://github.com/phalcon/cphalcon
# cd cphalcon/
# git checkout 2.1.x
# zephir build --backend=ZendEngine3
Segmentation fault (core dumped)

when trying to run zephir again, getting the message:

PHP Warning:  Illegal offset type in /root/zephir/Library/Passes/StaticTypeInference.php on line 284
PHP Parse error:  syntax error, unexpected 'f' (T_STRING), expecting ')' in /root/cphalcon/.temp/0.9.2a-dev/_root_cphalcon_phalcon_assets_filterinterface.zep.js.php on line 14