Fix confetty PTY handling in oneshot mode
Fix confetty PTY handling in oneshot mode

When asked to execute a command, do not mess with the terminal
in a way that would incur SIGTTOU when run in background.  This
means that a backgrounded confetty can actually exit rather
than block waiting to be run in foreground.  This won't work
with running a *console* in background, but that really doesn't
make any sense.

michaelfardu/thinkconfluent,michaelfardu/thinkconfluent,whowutwut/confluent,jjohnson42/confluent,michaelfardu/thinkconfluent,jjohnson42/confluent,jjohnson42/confluent,xcat2/confluent,whowutwut/confluent,chenglch/confluent,jufm/confluent,michaelfardu/thinkconfluent,xcat2/confluent,whowutwut/confluent,jjohnson42/confluent,chenglch/confluent,jufm/confluent,xcat2/confluent,chenglch/confluent,chenglch/confluent,jjohnson42/confluent,jufm/confluent,xcat2/confluent,jufm/confluent,whowutwut/confluent,jufm/confluent,michaelfardu/thinkconfluent,xcat2/confluent,chenglch/confluent