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
UniValue entry(UniValue::VOBJ);
            if (involvesWatchonly || (::IsMine(*pwallet, r.destination) & ISMINE_WATCH_ONLY)) {
                entry.pushKV("involvesWatchonly", true);
            }
            MaybePushAddress(entry, r.destination);
            if (wtx.IsCoinBase())
            {
                if (wtx.GetDepthInMainChain(locked_chain) < 1)
                    entry.pushKV("category", "orphan");
                else if (wtx.IsImmatureCoinBase(locked_chain))
                    entry.pushKV("category", "immature");
                else
                    entry.pushKV("category", "generate");
            }
            else
            {
                entry.pushKV("category", "receive");
            }
            entry.pushKV("amount", ValueFromAmount(r.amount));
            if (pwallet->mapAddressBook.count(r.destination)) {
                entry.pushKV("label", label);
            }
            entry.pushKV("vout", r.vout);
            if (fLong)
                WalletTxToJSON(pwallet->chain(), locked_chain, wtx, entry);
            ret.push_back(entry);
        }
    }
}
UniValue listtransactions(const JSONRPCRequest& request)