I don't know, I only know that I cannot reproduce your issue. Try a clean clone instead.
Done. This is using the version available last time I downloaded the .zip, which was right after you made this post.
Exact same error. Before I tried it in a clean version, I tried and failed to get it to work by fixing an apparent error in RFCUtils, where unit.Kill(iBarbarian, False) seems to be backwards (It should be False, iBarbarian).
Two turns after the save is when it crashes. And here's the error:
Traceback (most recent call last):
File "BugEventManager", line 400, in _handleDefaultEvent
File "CvRFCEventHandler", line 603, in onBeginGameTurn
File "Stability", line 53, in checkTurn
File "Stability", line 581, in completeCollapse
File "Stability", line 491, in secedeCities
File "Stability", line 556, in secedeCity
File "RFCUtils", line 1887, in flipOrCreateDefenders
File "RFCUtils", line 1855, in flipUnits
File "RFCUtils", line 1861, in flipUnit
File "RFCUtils", line 182, in makeUnit
RuntimeError: unidentifiable C++ exception