IndexError in multiprocessing async_results

[ArtPoon]

Traceback (most recent call last):
  File "kamphir.py", line 447, in <module>
    decay=args.toldecay)
  File "kamphir.py", line 303, in abc_mcmc
    next_score = self.evaluate()
  File "kamphir.py", line 264, in evaluate
    results = [r.get() for r in async_results]
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/pool.py", line 554, in get
    raise self._value
IndexError: list index out of range

[ArtPoon]

There must have been an exception thrown in compute(), but unfortunately no informative messages get through the multiprocessing layer. Add try..except clauses in compute() to hopefully catch this exception when it comes up (another rare stochastic event).