Bug in luatex handling of hidden dirs in TEXMFVAR

Hi,

I think I have tripped over a bug where luatex from texlive 2025 rejects
unix hidden directories in TEXMFVAR. The document compiled fine with
texlive 2023 (sorry, I have not tried 2024).

Running
    TEXMFHOME=.texmfhome TEXMFVAR=.texmfhome/texmfvar luatex doc.tex
on a very basic document fails with
    luaotfload | load : FATAL ERROR
    luaotfload | load :   × Failed to load "fontloader" module "basics-gen".
    luaotfload | load :   × Error message:
    luaotfload | load :     × "...2025-texmfdist/tex/luatex/luaotfload/luaotfload-init.lua:301: system : no writeable cache path, quiting".
(actually, only the `TEXMFVAR` variable is needed).

This only happens if the `TEXMFVAR` is a relative path with some component
starting with a dot -- `TEXMFVAR=texmfhome/texmfvar` works, as does
`TEXMFVAR=/tmp/.texmfhome/texmfvar`.

Possibly this is an incompatibility with the luaotfload package, but
note that using a hacked-together
- luatex-from-tl2025 and luaotfload-from-tl2023 shows the same problem
- luatex-from-tl2023 and luaotfload-from-tl2025 compiles fine

Version details:
Texlive 2023 has `luatex --version`
    This is LuaTeX, Version 1.17.0 (TeX Live 2023/nixos.org)
    Development id: 7581
Texlive 2025 has `luatex --version`
    This is LuaTeX, Version 1.21.0 (TeX Live 2025/nixos.org)
    Development id: 7667

Basic document:
    \input luaotfload.sty
    TEST
    \bye

Let me know if any more info would be helpful,
Ben