Unfortunately, it's a known issue since we moved to qcow2 images. I've tried to fix it (and the new regex I've implemented works when tested in a regex tester) but it hasn't fixed it. :( My PHP skills are pretty rudimentary, so I think I need to get someone who knows it better to have a look...

However, in the meantime, you can download them direct from the mirror. Look for the latest v15.x version of each one.

Hopefully can find what you need there. If not, please ask.

Thanks for that workaround!