message: Fix open file for pickle in common.py
diff: @@ -476,7 +476,7 @@ class ExecutionStateGatherer(object):
  def dump(self, fname, obj):
  import pickle
  - with open(fname, 'w') as fp:
  + with open(fname, 'wb') as fp:
  pickle.dump(obj, fp)
  def undump(self, fname):
  