Steps to replicate the issue (include links if applicable):
What happens?:
Implementation Z13577 fails
What should have happened instead?:
Implementation Z13577 should probably succeed?
It might be due to the unusual way the tester is written. But then again, it does work for the JavaScript implementation Z15755.
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):