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
{
                                    {"address", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "A key-value pair. The key (string) is the bitcoin address, the value (float or string) is the amount in " + CURRENCY_UNIT + ""},
                                },
                                },
                            {"", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "",
                                {
                                    {"data", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "A key-value pair. The key must be \"data\", the value is hex-encoded data"},
                                },
                            },
                        },
                    },
                    {"locktime", RPCArg::Type::NUM,  "0", "Raw locktime. Non-0 value also locktime-activates inputs"},
                    {"options", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "",
                        {
                            {"changeAddress", RPCArg::Type::STR_HEX,  "pool address", "The bitcoin address to receive the change"},
                            {"changePosition", RPCArg::Type::NUM,  "random", "The index of the change output"},
                            {"change_type", RPCArg::Type::STR,  "set by -changetype", "The output type to use. Only valid if changeAddress is not specified. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\"."},
                            {"includeWatching", RPCArg::Type::BOOL,  "false", "Also select inputs which are watch only"},
                            {"lockUnspents", RPCArg::Type::BOOL,  "false", "Lock selected unspent outputs"},
                            {"feeRate", RPCArg::Type::AMOUNT,  "not set: makes wallet determine the fee", "Set a specific fee rate in " + CURRENCY_UNIT + "/kB"},
                            {"subtractFeeFromOutputs", RPCArg::Type::ARR,  "empty array", "A json array of integers.\n"
                            "                              The fee will be equally deducted from the amount of each specified output.\n"
                            "                              Those recipients will receive less bitcoins than you enter in their corresponding amount field.\n"
                            "                              If no outputs are specified here, the sender pays the fee.",
                                {
                                    {"vout_index", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The zero-based output index, before a change output is added."},
                                },
                            },
                            {"replaceable", RPCArg::Type::BOOL,  "false", "Marks this transaction as BIP125 replaceable.\n"
                            "                              Allows this transaction to be replaced by a transaction with higher fees"},