Fix persist read for linearizeCFG only
IRClosure should copy arity when they are cloned
IR persist recreates UNRESCUED_REGION_LABEL.  Change from == to equals.
Whoops inverting this conditional worked for too many things
Dump full stack trace if persist read debugging is on
Hack around hashing problem with cloned IRClosures
print stack trace since we are screwed at this point and I want to see error dumped
Fix encoding Zsuper