PHP Fatal error after update PHP 7.0 to PHP 7.1

Oddly, I wanted to test out the "clone" function of the parameters, and by a miracle, the error disappeared ;-) I do not know why, but it's cool.

Before:

    // Allow other modules to specify what properties should be compared when
    // determining whether or not to combine line items.
    drupal_alter('commerce_cart_product_comparison_properties', $comparison_properties, clone($line_item));

After:

    // Allow other modules to specify what properties should be compared when
    // determining whether or not to combine line items.
    $cloned_lineitem = clone($line_item);
    drupal_alter('commerce_cart_product_comparison_properties', $comparison_properties, $cloned_lineitem);

@paintingguy,
my PHP version for apache2 is still 7.0.
my problem was the PHP (cli) version, it's now 7.1 on an the ubuntu server 16.04. So I guess I only had problem when a use the drush command...

If you are on ubuntu like you can switch the version of PHP by set the php alternative:

steve@nsxxxxxx:~⟫ php -v
PHP 7.1.0-5+deb.sury.org~xenial+1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.1.0-5+deb.sury.org~xenial+1, Copyright (c) 1999-2016, by Zend Technologies
steve@nsxxxxxx:~⟫ sudo update-alternatives --set php $(sudo update-alternatives --list php | grep "php7.0")
update-alternatives: utilisation de « /usr/bin/php7.0 » pour fournir « /usr/bin/php » (php) en mode manuel
steve@nsxxxxxx:~⟫ php -v
PHP 7.0.14-2+deb.sury.org~xenial+1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.14-2+deb.sury.org~xenial+1, Copyright (c) 1999-2016, by Zend Technologie
steve@nsxxxxxx:~⟫ sudo update-alternatives --set php $(sudo update-alternatives --list php | grep "php7.1")
update-alternatives: utilisation de « /usr/bin/php7.1 » pour fournir « /usr/bin/php » (php) en mode manuel
steve@nsxxxxxx:~⟫ php -v
PHP 7.1.0-5+deb.sury.org~xenial+1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.1.0-5+deb.sury.org~xenial+1, Copyright (c) 1999-2016, by Zend Technologies