message: session resets driver to simulate=False only if already connected
diff: @@ -113,10 +113,11 @@ class Session(object):
  try:
  # TODO (artyom, 20171005): this will go away
  # once robot / driver simulation flow is fixed
  + prev_simulate_state = robot._driver.simulating
  robot._driver.simulating = True
  exec(self._protocol, {})
  finally:
  - robot._driver.simulating = False
  + robot._driver.simulating = prev_simulate_state
  unsubscribe()
  # Accumulate containers, instruments, interactions from commands
  