A complete bitcoin implementation in Python?
That strongly depends on your definition of complete. There are a number of implementations that implement parts of the Bitcoin node functionality. For example cdecker/pycoin has a solid network implementation, but does not include wallet management code and validation logic. richardkiss/pycoin on the other hand has some of the wallet logic, but lacks networking. Other libraries include:


vbuterin/pybitcointools
petertodd/python-bitcoinlib


But as far as I know there is no standalone client that includes a wallet as well as the networking code.