A mismatch between implementation occurred on the bech32 prefix for
regtest mode. Bitcoin Core decided to use the bcrt prefix in order
for it to be distinguishable from the testnet prefix. btcd on the other
hand uses the same prefix as testnet because of lack of a separate
prefix specified in this BIP.
Core: https://github.com/bitcoin/bitcoin/issues/12314 btcd: https://github.com/btcsuite/btcd/pull/1150