The read builtin erroneously consumes null bytes

Hi,

Consider the following test case. It demonstrates NUL being consumed by the read builtin, rather than by cat(1) as it should have been.

$ printf 'a\n\0bc' | dash -c 'read x; cat' | od -An -t x1 -c
  62  63
   b   c

This defect may be attributable to https://git.kernel.org/pub/scm/utils/dash/dash.git/tree/src/input.c?h=v0.5.13.4#n411.

Incidentally, it results in tests #5510, #5558 and #6020 failing for git v2.54.0.

-- 
Kerin Millar