Fixed C extension sandbox behavior
bug #1256 Fixed C extension sandbox behavior (tucksaun)

This PR was squashed before being merged into the master branch (closes #1256).

Discussion
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Fixed C extension sandbox behavior

fixes #1254

Commits
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40bba0e Fixed C extension sandbox behavior
Revert "merged branch Cottser/master (PR #1071)"

This reverts commit 2f5c9899a4088fce3bb6325d96232cd1978161e4, reversing
changes made to 4e7094f6a3831dc86b4963d805c4567f4076fce3.

Conflicts:
	lib/Twig/Environment.php
bumped version to 1.15