This is a Parrot bug. Recently the Parrot team have been working to clean up memory leaks in context handling, and as a result we're starting to see "double free" errors on exit again. Running Rakudo with Parrot's -G flag avoids the backtrace.
I'll leave this ticket open for now but mark it as "stalled" until we can find out what's happening in Parrot's context handling. Pm
