message: [wallet] CreateTransaction: simplify change address check
  backports bitcoin/bitcoin@709f8685ac37510aa145ac259753583c82280038
diff: @@ -125,7 +125,7 @@ PairResult CWallet::getNewAddress(CTxDestination& ret, const std::string address
  if (!GetKeyFromPool(newKey, type)) {
  // inform the user to top-up the keypool or unlock the wallet
  return PairResult(false, new std::string(
  - "Keypool ran out, please call keypoolrefill first, or unlock the wallet."));
  + _("Keypool ran out, please call keypoolrefill first, or unlock the wallet.")));
  }
  CKeyID keyID = newKey.GetID();
  @@ -2560,9 +2560,10 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend,
  // Reserve a new key pair from key pool
  CPubKey vchPubKey;
  - bool ret;
  - ret = reservekey.GetReservedKey(vchPubKey, true);
  - assert(ret); // should never fail, as we just unlocked
  + if (!reservekey.GetReservedKey(vchPubKey, true)) {
  + strFailReason = _("Can't generate a change-address key. Please call keypoolrefill first.");
  + return false;
  + }
  scriptChange = GetScriptForDestination(vchPubKey.GetID());
  }
  