Units tests failed on OSX and Linux

Created by: Johann-S

Due to this commit https://github.com/twbs/bootstrap/commit/a14451deb3b8368de76aad6e728b27032bf8097a

job : https://travis-ci.org/twbs/bootstrap/jobs/217756286

Maybe @Deilv, do you have any idea why ?

Edit maybe it would be better to move unit test relative to this commit in a visuel unit test