merged branch fabpot/twig-c-bug (PR #920)

This PR was merged into the master branch.

Commits
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df13370 added a missing test
33e690b fixed some tests when the extension is not enabled
51e707f merged branch char101/fix-ext-retval (PR #921)
014f459 added some missing test for Template::getAttribute()
e8d12da Fix empty string comparison
4311df3 added some missing test for Template::getAttribute()

Discussion
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The C extension does not behave in the same way as the PHP code

The added test shows that the C extension does not behave in the same way as the PHP code. I have no idea why. The problem is probably around line 1033 in the extension code: https://github.com/fabpot/Twig/blob/master/ext/twig/twig.c#L1033

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by stof at 2012-12-05T17:07:00Z

The testsuite is broken when you run it without the C Twig extension. The test should be skipped when ``useExt`` is ``true`` and the extension is not available