I worry about us doing toASCIIString here.

Digging through the call chain, the code ends up doing the equivalent of:
   `new URL(templateConfigFile.toURI().toASCIIString())`
so my gut feel is that we should just do `toString()`, given we're going to pass that string back into the URL constructor.

But I'll merge this pull request - we're already using toASCIIString in the method below, which you haven't touched.