tl2020 pretest begin

[Akira Kakuto]

Dear Uwe Siart,

> Install went smooth on Win7. But every call of lualatex invokes a remake
> of lualatex.fmt - over and over again. It starts with:
>
> -------
> This is LuaTeX, Version 1.12.0 (TeX Live 2020/W32TeX)

Probably you obtained a bit old one.
It was revision 54023 that I changed the engine of
lualatex from luatex to luahbtex.

Thanks,
Akira