Use SimpleReduceHandler to support encoding and decoding of OrderedDict

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extra : rebase_source : f613e5e8c1ea0baf1d737353aec53349b8be1d4a
extra : histedit_source : 75a9f14fc4b6664c040eeb5311e18ee0786635a6%2C030200d658d07920863ff57423b354ab855ea981
Update SimpleReduceHandler.restore to better follow the protocol.