Can NUL bytes be removed from the installer output?

I had to patch vixen (the Xen PV-in-HVM shim) just for the NetBSD domU installer due to NUL characters in the installer output:

https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg01191.html

That patch is not currently part of the official branch and I don't know if it will be integrated. Is it possible for the character encoding or
something to be changed so there are no NUL bytes any more?

Thanks, Sarah