'run a command on the zone.  This is only needed for implementing
put_file() get_file() so that we don\'t have to read the whole file
into memory.
compared to exec_command() it looses some niceties like being able to
return the process\'s exit code immediately.'

def _buffered_exec_command(self, cmd, stdin=subprocess.PIPE):

    local_cmd = [self.zlogin_cmd, self.zone, cmd]
    local_cmd = map(to_bytes, local_cmd)
    display.vvv(('EXEC    %s' % local_cmd), host=self.zone)
    p = subprocess.Popen(local_cmd, shell=False, stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    return p
