While trying to lock back the itf in low noise 3 the automation process was stuck because IMC and DET process were asking opposite states for each other.
It occured at 12h39 UTC as showned the SDB1 fast_shutter flag.
2018-10-21T12:32:37.014Z ITF_LOCK [DOWN.run] ezca: V1:GRD-DET_MAIN_REQUEST => SHUTTER_CLOSED
the slow shutter cannot be closed while Michelson fringes are flashing. The question is why ITF_LOCK made this request while it is in the DOWN state, I can't find it anywhere in the ITF_LOCK.py code.
To prevent the DET_MAIN from being in an infinite loop of trying to close the slow shutter, added a check that after 5 failed attempts it will go into the UNSAFE_B1p dead end state, and wait there for some action.
