https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
{
    const auto& address_book_it = m_address_book.find(dest);
    if (address_book_it == m_address_book.end()) return nullptr;
    if ((!allow_change) && address_book_it->second.IsChange()) {
        return nullptr;
    }
    return &address_book_it->second;
}
bool CWallet::UpgradeWallet(int version, bilingual_str& error)