[PVG, RO, RSS, Principia] Launch to target LAN doesn't launch the rocket (dev branch)

[mmomtchev]

On the dev branch with RO, RSS and Principia, when launching to target LAN:

• starts the countdown and displays Autopilot status: Pre launch
• about 10 seconds before the launch, the autopilot button disengages, the countdown continues; pressing again the Engage autopilot button is blocked (it immediately reverts)
• once the countdown reaches 0, nothing happens, however pressing the Engage autopilot button at this point will actually launch the rocket

[mmomtchev]

After engaging the autopilot:

After pressing Launch to target LAN:

At about 10 seconds left to launch (immediately after the final countdown starts):

[lamont-granquist]

yeah that ones been around for months, i've just been lazy about fixing it...

should be fixed by #1856