[tlbuild] Build problem. Luatex

[Karl Berry]

    cp: ./print.c and ./../../libs/lua51/print.c are identical (not copied).

Are you trying to build in the same directory as the sources?
That is known not to work.  That's my only idea ...

    Is luatex ready for mainstream use now then?

It is possible to write useful, nontrivial scripts with it, so it is
good to have it.

As a typesetting engine, it is not up to pdftex (let alone tex) levels
of reliability and should still be considered beta.  (This from Taco.)
But it does basically work, in my experience ...

karl