Function reset_spends 

pub fn reset_spends(
    wallet_transactions: &mut HashMap<TxId, WalletTransaction>,
    invalid_txids: Vec<TxId>,
)

Resets the spending transaction field of all outputs that were previously spent but became unspent due to a spending transactions becoming invalid.

invalid_txids are the id’s of the invalidated spending transactions. Any outputs in the wallet_transactions matching these spending transactions will be reset back to None.