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
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp))
        return NullUniValue;
    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2) {
        throw std::runtime_error(
            RPCHelpMan{"bumpfee",
                "\nBumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.\n"
                "An opt-in RBF transaction with the given txid must be in the wallet.\n"
                "The command will pay the additional fee by reducing change outputs or adding inputs when necessary. It may add a new change output if one does not already exist.\n"
                "If `totalFee` is given, adding inputs is not supported, so there must be a single change output that is big enough or it will fail.\n"
                "All inputs in the original transaction will be included in the replacement transaction.\n"
                "The command will fail if the wallet or mempool contains a transaction that spends one of T's outputs.\n"
                "By default, the new fee will be calculated automatically using estimatesmartfee.\n"
                "The user can specify a confirmation target for estimatesmartfee.\n"
                "Alternatively, the user can specify totalFee, or use RPC settxfee to set a higher fee rate.\n"
                "At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee\n"
                "returned by getnetworkinfo) to enter the node's mempool.\n",
                {
                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The txid to be bumped"},
                    {"options", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "",
                        {
                            {"confTarget", RPCArg::Type::NUM,  "fallback to wallet's default", "Confirmation target (in blocks)"},
                            {"totalFee", RPCArg::Type::NUM,  "fallback to 'confTarget'", "Total fee (NOT feerate) to pay, in satoshis.\n"
            "                         In rare cases, the actual fee paid might be slightly higher than the specified\n"
            "                         totalFee if the tx change output has to be removed because it is too close to\n"
            "                         the dust threshold."},
                            {"replaceable", RPCArg::Type::BOOL,  "true", "Whether the new transaction should still be\n"