Tried that.  Things like telnet constantly read.  It works
sometimes, not others, ...

I tried various ways to ``guess'' what the app was doing and
either apply Nagle or not.  I could get it to work pretty
regularly with 9P but it would break with other things.

I finally gave up and took it out since at least once a month
it would brak something.  I tried it as an option for a while
but the only thing anyone wanted it for was telnet and we just
don't do that anymore, ssh has replaced it and our window system
line buffers.