Continue to return None when we encounter a known transaction in add_transaction
Continue to return None when we encounter a known transaction in add_transaction

shahankhatch/pyethereum,ethereum/pyethereum,karlfloersch/pyethereum,pipermerriam/pyethereum,ethereum/pyethereum,shahankhatch/pyethereum,pipermerriam/pyethereum,karlfloersch/pyethereum