process SIGWINCH unless stdin is a TTY
Some process managers such as foreman and daemontools rely on
unicorn not daemonizing, but we still want to be able to process
SIGWINCH in that case.
stdout and stderr may be redirected to a pipe (for cronolog or
similar process), so those are less likely to be attached to a TTY
than stdin. This also allows users to process SIGWINCH when running
inside a regular terminal if they redirect stdin to /dev/null.
Reported-by: Dan Moore <dan@vaporwa.re>
References: <etPan.
555b4293.
5b47a5b7.e617@danbookpro>
<
20150519232858.GA23515@dcvr.yhbt.net>