Arisa doesn't expect helper message variables to contain other variables

[violine1101]

The Problem

If a helper message variable contains another variable, Arisa might not resolve it correctly. This is currently not an issue yet, but the proposed change in mojira/helper-messages#62 would break Arisa. If that PR is merged without Arisa being adjusted, this would turn into a bug.

Expected behavior

Arisa should be able to resolve all variables inside of variables up to a certain point, so that variables can include other variables, but only up to a certain limit (so that Arisa doesn't get stuck in an infinite loop). Here's an example of how I did it in JavaScript: mojira/helper-messages@0c44006#diff-36f8d737c0d72482b317e9b95c615dc2

[urielsalis]

ideally you add the ones you are using into the test, and the test checks that they exist :/