bug#24941: Early termination bug in grep 2.26

[Norihiro Tanaka]

On Tue, 15 Nov 2016 11:35:15 -0800
Jim Meyering <address@hidden> wrote:

> I suppose you mean in addition to the S_ISFIFO test? That sounds good.
> We should retain the optimization when reading from stdin that is a
> non-pipe.

This can also happen in stdin.  If we redirect stdout to /dev/null,
grep-2.26 exits immediately and prompt is returned.

- grep-2.25

$ grep . >/dev/null
a  <<input a and newline
b  <<input b and newline
c  <<input c and newline

- grep-2.26

$ src/grep . >/dev/null
a  <<input a and newline
$