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
for (const COutput& out : vecOutputs) {
        CTxDestination address;
        const CScript& scriptPubKey = out.tx->tx->vout[out.i].scriptPubKey;
        bool fValidAddress = ExtractDestination(scriptPubKey, address);
        if (destinations.size() && (!fValidAddress || !destinations.count(address)))
            continue;
        UniValue entry(UniValue::VOBJ);
        entry.pushKV("txid", out.tx->GetHash().GetHex());
        entry.pushKV("vout", out.i);
        if (fValidAddress) {
            entry.pushKV("address", EncodeDestination(address));
            auto i = pwallet->mapAddressBook.find(address);
            if (i != pwallet->mapAddressBook.end()) {
                entry.pushKV("label", i->second.name);
            }
            if (scriptPubKey.IsPayToScriptHash()) {
                const CScriptID& hash = boost::get<CScriptID>(address);
                CScript redeemScript;
                if (pwallet->GetCScript(hash, redeemScript)) {
                    entry.pushKV("redeemScript", HexStr(redeemScript.begin(), redeemScript.end()));
                    
                    CTxDestination witness_destination;
                    if (redeemScript.IsPayToWitnessScriptHash()) {
                        bool extracted = ExtractDestination(redeemScript, witness_destination);
                        assert(extracted);
                        
                        const WitnessV0ScriptHash& whash = boost::get<WitnessV0ScriptHash>(witness_destination);
                        CScriptID id;
                        CRIPEMD160().Write(whash.begin(), whash.size()).Finalize(id.begin());
                        CScript witnessScript;