Fix invalid 'args' and 'kwargs' decoding in python3

When we set pass_arguments=True, we should unpickle
'args' and 'kwargs' first.

Without it '_decode_from_spooler' will fail on 'decoding' their
packed by pickle data, because pickled data has 'bytes' type.
Merge pull request #761 from ykhalyavin/fix_pass_arguments

Fix invalid 'args' and 'kwargs' decoding in python3