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
break;
            case feebumper::Result::WALLET_ERROR:
                throw JSONRPCError(RPC_WALLET_ERROR, errors[0]);
                break;
            default:
                throw JSONRPCError(RPC_MISC_ERROR, errors[0]);
                break;
        }
    }
    
    if (!feebumper::SignTransaction(pwallet, mtx)) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Can't sign transaction.");
    }
    
    uint256 txid;
    if (feebumper::CommitTransaction(pwallet, hash, std::move(mtx), errors, txid) != feebumper::Result::OK) {
        throw JSONRPCError(RPC_WALLET_ERROR, errors[0]);
    }
    UniValue result(UniValue::VOBJ);
    result.pushKV("txid", txid.GetHex());
    result.pushKV("origfee", ValueFromAmount(old_fee));
    result.pushKV("fee", ValueFromAmount(new_fee));
    UniValue result_errors(UniValue::VARR);
    for (const std::string& error : errors) {
        result_errors.push_back(error);
    }
    result.pushKV("errors", result_errors);
    return result;
}
UniValue rescanblockchain(const JSONRPCRequest& request)