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
},
                RPCExamples{
            "\nSend two amounts to two different addresses:\n"
            + HelpExampleCli("sendmany", "\"\" \"{\\\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\\\":0.01,\\\"1353tsE8YMTA4EuV7dgUXGjNFf9KpVvKHz\\\":0.02}\"") +
            "\nSend two amounts to two different addresses setting the confirmation and comment:\n"
            + HelpExampleCli("sendmany", "\"\" \"{\\\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\\\":0.01,\\\"1353tsE8YMTA4EuV7dgUXGjNFf9KpVvKHz\\\":0.02}\" 6 \"testing\"") +
            "\nSend two amounts to two different addresses, subtract fee from amount:\n"
            + HelpExampleCli("sendmany", "\"\" \"{\\\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\\\":0.01,\\\"1353tsE8YMTA4EuV7dgUXGjNFf9KpVvKHz\\\":0.02}\" 1 \"\" \"[\\\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\\\",\\\"1353tsE8YMTA4EuV7dgUXGjNFf9KpVvKHz\\\"]\"") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("sendmany", "\"\", {\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\":0.01,\"1353tsE8YMTA4EuV7dgUXGjNFf9KpVvKHz\":0.02}, 6, \"testing\"")
                },
    };
    if (request.fHelp || !help.IsValidNumArgs(request.params.size())) {
        throw std::runtime_error(help.ToString());
    }
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    auto locked_chain = pwallet->chain().lock();
    LOCK(pwallet->cs_wallet);
    if (pwallet->GetBroadcastTransactions() && !pwallet->chain().p2pEnabled()) {
        throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
    }
    if (!request.params[0].isNull() && !request.params[0].get_str().empty()) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Dummy value must be set to \"\"");
    }
    UniValue sendTo = request.params[1].get_obj();
    mapValue_t mapValue;
    if (!request.params[3].isNull() && !request.params[3].get_str().empty())
        mapValue["comment"] = request.params[3].get_str();