When this happens, the terminal is under control and less can't take it. I've proposed a patch to libedit to avoid doing this if stdout is not a tty, and forwarded it along to the upstream mailing list for discussion there. I will also propose a merge shortly.
Ok so the real problem is actually this:
ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 opost isig icanon echo ...}) = 0
When this happens, the terminal is under control and less can't take it. I've proposed a patch to libedit to avoid doing this if stdout is not a tty, and forwarded it along to the upstream mailing list for discussion there. I will also propose a merge shortly.