asciidoctor/asciidoctor — pull request #964 by Mogztter (2014-05-25 15:13:28+00:00)
Title: Fix "sh [: unexpected operator" when running run-tests.sh

POSIX sh doesn't understand == for string equality, as that is a bash-ism. Use = instead.
http://stackoverflow.com/questions/3411048/unexpected-operator-in-shell-programming