Thanks for your answer. I had tried this before and it didn't work. I was really puzzled since I had seen that answer in many places in the forum and on the wiki. It turns out it was a copy/paste issue with the single quotes... My zen was tested again.
Ah, right, sorry. Discourse annoyingly automatically replaces the ASCII single quote with unicode fancy quotes, which wreaks havoc on copying and pasting some expressions.
I found a setting in discourse that claims to disable this behavior so that we won't have similar issues. Added some tests below