Procedural SRB missing nozzle causes physics issues.

[jbengtson]

Using Principia Cauchy, KSP 1.2.2, Real Solar System, Realism Overhaul.

Launch vessel with a procedural SRB to orbit.
Return to Space Center.
Switch to vessel.
Nozzle will be missing from the procedural SRB.

If the SRB is attached to a decoupler and it is staged the SRB (and any other parts on that vessel) will be gin spinning uncontrollably. In addition, a craft with a procedural SRB that is in physics-less timewarp (100x in my case) that hits the atmosphere and drops out of timewarp will being spinning uncontrollably.

[eggrobin]

This is a resurgence of #1421, except it happens when the vessel is reloaded from a state saved in flight rather than when launching. This condition will have to be adjusted, but we must be careful not to skip frames in situations where we should not.

[eggrobin]

This appears trickier than expected: #1421 was solved by skipping advancing time (and setting the body frames, etc.) on frames where the active vessel's orbit driver's last update mode is TRACK_Phys and the current update mode is IDLE, of which there are two when loading the vessel on the pad. When loading the vessel in flight, we instead have two frames where the last update mode is TRACK_Phys and the current update mode is UPDATE, but skipping those does not solve the problem, and it further causes principia to crash on timewarp (skipping random frames probably break our expectations).

[eggrobin]

I have replicated this bug without Principia, so I think it's not ours, although the symptoms are the same as those of #1421, which was our fault. I will ask @Starwaster to reopen Starwaster/ProceduralParts#3 to track this.

@jbengtson, can you confirm that this occurs in the absence of Principia? (you may want to backup your save before removing Principia).