add region state version and reinstate YouAreDead exception in region report

The state version will ensure we don't have network-related races (e.g. the one I reported in some other bug -

RS: send report {R1} ...
M: close R1
RS: I closed R1
M ... receive report {R1}
M: you shouldn't have R1, die

).
Then we can revert the change that removed YouAreDead exception... RS in incorrect state should be either brought into correct state or killed because it means there's some bug; right now if double assignment happens (I found 2 different cases just this week ) master lets RS with incorrect assignment keep it forever.