message: sets driver.simulating flag during protocol simulation, instead of disconnecting from actual robot
diff: @@ -113,10 +113,10 @@ class Session(object):
  try:
  # TODO (artyom, 20171005): this will go away
  # once robot / driver simulation flow is fixed
  - robot._driver.disconnect()
  + robot._driver.simulating = True
  exec(self._protocol, {})
  finally:
  - robot._driver.connect()
  + robot._driver.simulating = False
  unsubscribe()
  # Accumulate containers, instruments, interactions from commands
  