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
{
    if (request.fHelp || request.params.size() != 1)
        throw std::runtime_error(
            RPCHelpMan{"verifytxoutproof",
                "\nVerifies that a proof points to a transaction in a block, returning the transaction it commits to\n"
                "and throwing an RPC error if the block is not in our best chain\n",
                {
                    {"proof", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex-encoded proof generated by gettxoutproof"},
                },
                RPCResult{
            "[\"txid\"]      (array, strings) The txid(s) which the proof commits to, or empty array if the proof can not be validated.\n"
                },
                RPCExamples{""},
            }.ToString()
        );
    CDataStream ssMB(ParseHexV(request.params[0], "proof"), SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS);
    CMerkleBlock merkleBlock;
    ssMB >> merkleBlock;
    UniValue res(UniValue::VARR);
    std::vector<uint256> vMatch;
    std::vector<unsigned int> vIndex;
    if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) != merkleBlock.header.hashMerkleRoot)
        return res;
    LOCK(cs_main);
    const CBlockIndex* pindex = LookupBlockIndex(merkleBlock.header.GetHash());
    if (!pindex || !chainActive.Contains(pindex) || pindex->nTx == 0) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
    }