"Test on linux", "Test on darwin".

Test on $CIRRUS_OSLooks like it matched $CI instead of $CIRRUS_OS.
Try wrapping it in curly braces
I think, it should stop match by non-word symbols, something like /(\$[A-Z_])[^A-Z_]/ (not sure about digits in env var names).
The issue was that $CIRRUS_OS variable wasn't available at parsing time. I've added a test and fixed the issue. Should be available in ~1 hour.
Thank you!
I confirm it fixed:
