[luatex] normaldeviate requires a number?

[David Carlisle]

This document with pdftex


\ifx\directlua\undefined\else
 \let\pdfrandomseed\randomseed
 \let\pdfsetrandomseed\setrandomseed
 \let\pdfnormaldeviate\normaldeviate
 \let\pdfuniformdeviate\uniformdeviate
\fi

\pdfsetrandomseed 999

\immediate\write20{A: \pdfnormaldeviate}
\immediate\write20{B: \pdfnormaldeviate}
\immediate\write20{C: \pdfuniformdeviate 100}
\immediate\write20{D: \pdfuniformdeviate 100}

\bye

produces terminal output of

A: -65925
B: 114111
C: 5
D: 74


I'd have expected from the luatex manual that luatex would be the same
but it gives

This is LuaTeX, Version 1.0.1 (TeX Live 2017/dev)
 restricted system commands enabled.
(./rnd.tex
! Missing number, treated as zero.


You get the expected output from

\immediate\write20{A: \pdfnormaldeviate 0}
\immediate\write20{B: \pdfnormaldeviate 0}

but then of course pdftex gives

A: -659250
B: 1141110


It appears that any number will work and \normaldeviate just gobbles a
following <number> without using it.

Would it be possible to have a pdftex compatible behaviour here, or if
the number is doing something, document in the manual what it does.

Thanks,

David