When the fee parameter is set to zero in the function prepare_transaction, it processes it like None, so the bit tries to predict fee by itself, but the expected behavior is that the fee of prepared transaction will be 0.

Reason:
I need this function to calculate inputs and outputs, and I calculate the fee myself, so there are situations when there are 100,000 satoshi on the address and I want to create a transaction with this amount an error occurs that there is not enough money on the address.