sass/sass-spec — pull request #62 by lunelson (2014-10-06 12:20:49+00:00)
Title: Add test for falsey return value of index function

Ruby sass recently changed this. As with map-get(), if you use index() to try to find the position of an item which is not present the function should return null, not false.

In this test, the second item should return null, and therefore not appear in the output.

https://github.com/sass/libsass/issues/512