https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
{
    LOCK(cs_wallet);
    m_wallet_flags |= flags;
    if (!WalletBatch(GetDatabase()).WriteWalletFlags(m_wallet_flags))
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
}
void CWallet::UnsetWalletFlag(uint64_t flag)
{
    WalletBatch batch(GetDatabase());
    UnsetWalletFlagWithDB(batch, flag);
}
void CWallet::UnsetWalletFlagWithDB(WalletBatch& batch, uint64_t flag)
{
    LOCK(cs_wallet);
    m_wallet_flags &= ~flag;
    if (!batch.WriteWalletFlags(m_wallet_flags))
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
}
void CWallet::UnsetBlankWalletFlag(WalletBatch& batch)
{
    UnsetWalletFlagWithDB(batch, WALLET_FLAG_BLANK_WALLET);
}
bool CWallet::IsWalletFlagSet(uint64_t flag) const