[tex-live] luaotfload tries to recompile an existing .luc file

[Karl Berry]

    So do you think it is a TeXLive bug?

I don't believe so.

My (shallow) understanding of TEXMFCACHE is written in the comment just
before the definition:

% First writable tree here is used by Lua(La)TeX for the font cache.
..
TEXMFCACHE = $TEXMFSYSVAR;$TEXMFVAR

Therefore it is intentional that there is more than one tree.  I do not
know the details of what luaotfload is doing (differently), or what it
should do (differently).  I hope Philipp and the other maintainers can
figure it out in response to your bug report there.  Thank you for
submitting the report there.

If $TEXMFSYSVAR was removed from the list, that would eliminate the
possibility of a system-wide fontcache for lua(la)tex fonts.  That
doesn't especially make sense to me.

Best,
Karl