We are currently using some deprecated code that will be removed or not workable in Twig 2.0.
- Make those updates now.
- Push our fixes upstream: https://github.com/twigphp/Twig/pull/1837
If/when Twig 2.x requires PHP 5.6, we will need to set the d.o packager to use 1.x and allow composer users to choose 2.x via #platform https://getcomposer.org/doc/06-config.md#platform
User interface changes
Data model changes
Should be none.