[tex-live] TL 2024: lua's file.is_writable() broken

[Karl Berry]

    Could anyone explain why io.open() does not accept absolute paths?

Werner - I mentioned the new restrictions of luatex prominently during
the pretest. The idea is to have the Lua level behave like the TeX level
wrt output paranoia, since people run lua(la)tex to typeset documents in
presumed safety, not have unfettered access to the entire
system. (texlua, otoh, does not have the restrictions, since its goal is
not typesetting.)

    And how to fix this?

One way to eliminate the restrictions entirely is to use --shell-escape,
as usual. Your idea of setting TEXMFOUTPUT also works, as long as you
don't mind that the pdf output and all else also goes there. There is
also the new TEXMF_OUTPUT_DIRECTORY, though I don't recommend using it
for this. It depends on what you're trying to do. -k