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
subobj.pushKV("address", EncodeDestination(embedded));
            subobj.pushKV("scriptPubKey", HexStr(subscript.begin(), subscript.end()));
            
            if (subobj.exists("pubkey")) obj.pushKV("pubkey", subobj["pubkey"]);
            obj.pushKV("embedded", std::move(subobj));
        } else if (which_type == TX_MULTISIG) {
            
            
            obj.pushKV("sigsrequired", solutions_data[0][0]);
            UniValue pubkeys(UniValue::VARR);
            for (size_t i = 1; i < solutions_data.size() - 1; ++i) {
                CPubKey key(solutions_data[i].begin(), solutions_data[i].end());
                pubkeys.push_back(HexStr(key.begin(), key.end()));
            }
            obj.pushKV("pubkeys", std::move(pubkeys));
        }
    }
    explicit DescribeWalletAddressVisitor(CWallet* _pwallet) : pwallet(_pwallet) {}
    UniValue operator()(const CNoDestination& dest) const { return UniValue(UniValue::VOBJ); }
    UniValue operator()(const CKeyID& keyID) const
    {
        UniValue obj(UniValue::VOBJ);
        CPubKey vchPubKey;
        if (pwallet && pwallet->GetPubKey(keyID, vchPubKey)) {
            obj.pushKV("pubkey", HexStr(vchPubKey));
            obj.pushKV("iscompressed", vchPubKey.IsCompressed());
        }
        return obj;
    }
    UniValue operator()(const CScriptID& scriptID) const