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
entry.pushKV("blockindex", wtx.nIndex);
        int64_t block_time;
        bool found_block = chain.findBlock(wtx.hashBlock, nullptr , &block_time);
        assert(found_block);
        entry.pushKV("blocktime", block_time);
    } else {
        entry.pushKV("trusted", wtx.IsTrusted(locked_chain));
    }
    uint256 hash = wtx.GetHash();
    entry.pushKV("txid", hash.GetHex());
    UniValue conflicts(UniValue::VARR);
    for (const uint256& conflict : wtx.GetConflicts())
        conflicts.push_back(conflict.GetHex());
    entry.pushKV("walletconflicts", conflicts);
    entry.pushKV("time", wtx.GetTxTime());
    entry.pushKV("timereceived", (int64_t)wtx.nTimeReceived);
    
    std::string rbfStatus = "no";
    if (confirms <= 0) {
        RBFTransactionState rbfState = chain.isRBFOptIn(*wtx.tx);
        if (rbfState == RBFTransactionState::UNKNOWN)
            rbfStatus = "unknown";
        else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125)
            rbfStatus = "yes";
    }
    entry.pushKV("bip125-replaceable", rbfStatus);
    for (const std::pair<const std::string, std::string>& item : wtx.mapValue)
        entry.pushKV(item.first, item.second);
}
static std::string LabelFromValue(const UniValue& value)