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
CAmount nAmount = AmountFromValue(request.params[1]);
    if (nAmount <= 0)
        throw JSONRPCError(RPC_TYPE_ERROR, "Invalid amount for send");
    
    mapValue_t mapValue;
    if (!request.params[2].isNull() && !request.params[2].get_str().empty())
        mapValue["comment"] = request.params[2].get_str();
    if (!request.params[3].isNull() && !request.params[3].get_str().empty())
        mapValue["to"] = request.params[3].get_str();
    bool fSubtractFeeFromAmount = false;
    if (!request.params[4].isNull()) {
        fSubtractFeeFromAmount = request.params[4].get_bool();
    }
    CCoinControl coin_control;
    if (!request.params[5].isNull()) {
        coin_control.m_signal_bip125_rbf = request.params[5].get_bool();
    }
    if (!request.params[6].isNull()) {
        coin_control.m_confirm_target = ParseConfirmTarget(request.params[6], pwallet->chain().estimateMaxBlocks());
    }
    if (!request.params[7].isNull()) {
        if (!FeeModeFromString(request.params[7].get_str(), coin_control.m_fee_mode)) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid estimate_mode parameter");
        }
    }
    EnsureWalletIsUnlocked(pwallet);
    CTransactionRef tx = SendMoney(*locked_chain, pwallet, dest, nAmount, fSubtractFeeFromAmount, coin_control, std::move(mapValue));
    return tx->GetHash().GetHex();
}
static UniValue listaddressgroupings(const JSONRPCRequest& request)