Improve __getstate__ for bootstrapinfo

This approach may be a little hacked, but it works for now and
if it breaks at some point in the future because of e.g. circular references
that bridge will have to be crossed then

bootstrapvz/base/bootstrapinfo.py

@@ -115,13 +115,22 @@ class BootstrapInformation(object):
 		return manifest_vars
 
 	def __getstate__(self):
-		state = self.__dict__.copy()
-		exclude_keys = ['source_lists', 'preference_lists', 'packages']
-		for key in exclude_keys:
-			# We may have been serialized before,
-			# so don't fail if the keys do not exist
-			if key in state:
-				del state[key]
+		from bootstrapvz.remote import supported_classes
+
+		def can_serialize(obj):
+			if hasattr(obj, '__class__') and hasattr(obj, '__module__'):
+				class_name = obj.__module__ + '.' + obj.__class__.__name__
+				return class_name in supported_classes or isinstance(obj, (BaseException, Exception))
+			return True
+
+		def filter_state(state):
+			if isinstance(state, dict):
+				return {key: filter_state(val) for key, val in state.items() if can_serialize(val)}
+			if isinstance(state, (set, tuple, list, frozenset)):
+				return type(state)(filter_state(val) for val in state if can_serialize(val))
+			return state
+
+		state = filter_state(self.__dict__)
 		state['__class__'] = self.__module__ + '.' + self.__class__.__name__
 		return state