luatex defect in texlive-2017

[ken@…]

From Karl Berry on the tlbuild list last Thursday:

Unfortunately, debugging code was left in the luatex 1.0.4 we
built for TL17, rendering io.popen useless.  Akira committed
the fix for this (r44518). This has no effect on most documents,
but where it's needed, it's needed, so it seems we should not
leave it broken for a year.

After consulting with Luigi, I also made another tiny commit 
(r44530) to (1) disable io.saved_popen [long story], and (2) 
change the luatex_date_info value. Unfortunately we cannot 
change the actual luatex version from 1.0.4 without inducing 
lots of other changes, e.g., in ConTeXt. So this is the best we 
can do.

The other changes in Build/source in the meantime are unimportant,
related to script packages and doc.

[ken@…]

r18818,