I just updated my vendors on a Symfony 2.8 project, getting Twig 1.26.0
I'm getting the following deprecation notice:

Referencing the "Twig_Extension_Core" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.

I tried to remove getName() method from my extension, everything is working like before, but the deprecation is still there. I guess is something inside Symfony itself