Function merge_account_data 

pub(crate) fn merge_account_data<ExtDB: DatabaseRef, N: Network, B: ForkBlockEnv>(
    accounts: impl IntoIterator<Item = Address>,
    active: &CacheDB<ExtDB>,
    active_journaled_state: &mut JournaledState,
    target_fork: &mut Fork<N, B>,
)

Clones the data of the given accounts from the active database into the fork_db This includes the data held in storage (CacheDB) and kept in the JournaledState.