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 (!params[1].isNull())
        fIncludeEmpty = params[1].get_bool();
    isminefilter filter = ISMINE_SPENDABLE;
    if(!params[2].isNull())
        if(params[2].get_bool())
            filter = filter | ISMINE_WATCH_ONLY;
    bool has_filtered_address = false;
    CTxDestination filtered_address = CNoDestination();
    if (!by_label && params.size() > 3) {
        if (!IsValidDestinationString(params[3].get_str())) {
            throw JSONRPCError(RPC_WALLET_ERROR, "address_filter parameter was invalid");
        }
        filtered_address = DecodeDestination(params[3].get_str());
        has_filtered_address = true;
    }
    
    std::map<CTxDestination, tallyitem> mapTally;
    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
        const CWalletTx& wtx = pairWtx.second;
        if (wtx.IsCoinBase() || !locked_chain.checkFinalTx(*wtx.tx)) {
            continue;
        }
        int nDepth = wtx.GetDepthInMainChain(locked_chain);
        if (nDepth < nMinDepth)
            continue;
        for (const CTxOut& txout : wtx.tx->vout)
        {
            CTxDestination address;
            if (!ExtractDestination(txout.scriptPubKey, address))
                continue;