Added reset_genesis to chain initialization from state

Author: vbuterin

ethereum/pow/chain.py

@@ -43,6 +43,7 @@ def __init__(self, genesis=None, env=None, coinbase=b'\x00' * 20, \
             self.state = genesis
             self.env = self.state.env
             print('Initializing chain from provided state')
+            reset_genesis = True
         elif "extraData" in genesis:
             self.state = state_from_genesis_declaration(
                 genesis, self.env)