travis run: https://travis-ci.org/bitcoin/bitcoin/jobs/406813397

```
rpc_psbt.py failed, Duration: 4 s
stdout:
2018-07-22T13:28:57.765000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_test_runner_20180722_132530/rpc_psbt_49
2018-07-22T13:29:00.531000Z TestFramework (ERROR): Assertion failed
Traceback (most recent call last):
  File "/home/travis/build/bitcoin/bitcoin/build/bitcoin-x86_64-unknown-linux-gnu/test/functional/test_framework/test_framework.py", line 160, in main
    self.run_test()
  File "/home/travis/build/bitcoin/bitcoin/build/bitcoin-x86_64-unknown-linux-gnu/test/functional/rpc_psbt.py", line 101, in run_test
    assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].converttopsbt, signedtx['hex'])
  File "/home/travis/build/bitcoin/bitcoin/build/bitcoin-x86_64-unknown-linux-gnu/test/functional/test_framework/util.py", line 105, in assert_raises_rpc_error
    assert try_rpc(code, message, fun, *args, **kwds), "No exception raised"
AssertionError: No exception raised
throw JSONRPCError(RPC_TYPE_ERROR, "Invalid amount for send");
        bool fSubtractFeeFromAmount = false;
        for (unsigned int idx = 0; idx < subtractFeeFromAmount.size(); idx++) {
            const UniValue& addr = subtractFeeFromAmount[idx];
            if (addr.get_str() == name_)
                fSubtractFeeFromAmount = true;
        }
        CRecipient recipient = {scriptPubKey, nAmount, fSubtractFeeFromAmount};
        vecSend.push_back(recipient);
    }
    EnsureWalletIsUnlocked(pwallet);
    
    std::shuffle(vecSend.begin(), vecSend.end(), FastRandomContext());
    
    CReserveKey keyChange(pwallet);
    CAmount nFeeRequired = 0;
    int nChangePosRet = -1;
    std::string strFailReason;
    CTransactionRef tx;
    bool fCreated = pwallet->CreateTransaction(*locked_chain, vecSend, tx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
    if (!fCreated)
        throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, strFailReason);
    CValidationState state;
    if (!pwallet->CommitTransaction(tx, std::move(mapValue), {} , keyChange, state)) {
        strFailReason = strprintf("Transaction commit failed:: %s", FormatStateMessage(state));
        throw JSONRPCError(RPC_WALLET_ERROR, strFailReason);
    }
    return tx->GetHash().GetHex();
}
static UniValue addmultisigaddress(const JSONRPCRequest& request)