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
auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        const CWallet::TxItems & txOrdered = pwallet->wtxOrdered;
        
        for (CWallet::TxItems::const_reverse_iterator it = txOrdered.rbegin(); it != txOrdered.rend(); ++it)
        {
            CWalletTx *const pwtx = (*it).second;
            ListTransactions(*locked_chain, pwallet, *pwtx, 0, true, ret, filter, filter_label);
            if ((int)ret.size() >= (nCount+nFrom)) break;
        }
    }
    
    if (nFrom > (int)ret.size())
        nFrom = ret.size();
    if ((nFrom + nCount) > (int)ret.size())
        nCount = ret.size() - nFrom;
    std::vector<UniValue> arrTmp = ret.getValues();
    std::vector<UniValue>::iterator first = arrTmp.begin();
    std::advance(first, nFrom);
    std::vector<UniValue>::iterator last = arrTmp.begin();
    std::advance(last, nFrom+nCount);
    if (last != arrTmp.end()) arrTmp.erase(last, arrTmp.end());
    if (first != arrTmp.begin()) arrTmp.erase(arrTmp.begin(), first);
    std::reverse(arrTmp.begin(), arrTmp.end()); 
    ret.clear();
    ret.setArray();
    ret.push_backV(arrTmp);
    return ret;
}
static UniValue listsinceblock(const JSONRPCRequest& request)