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
{
    const RPCHelpMan help{"decodescript",
                "\nDecode a hex-encoded script.\n",
                {
                    {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "the hex-encoded script"},
                },
                RPCResult{
            "{\n"
            "  \"asm\":\"asm\",          (string) Script public key\n"
            "  \"type\":\"type\",        (string) The output type (e.g. "+GetAllOutputTypes()+")\n"
            "  \"reqSigs\": n,         (numeric) The required signatures\n"
            "  \"addresses\": [        (json array of string)\n"
            "     \"address\"          (string) bitcoin address\n"
            "     ,...\n"
            "  ],\n"
            "  \"p2sh\":\"str\"          (string) address of P2SH script wrapping this redeem script (not returned if the script is already a P2SH).\n"
            "  \"segwit\": {           (json object) Result of a witness script public key wrapping this redeem script (not returned if the script is a P2SH or witness).\n"
            "    \"asm\":\"str\",        (string) String representation of the script public key\n"
            "    \"hex\":\"hexstr\",     (string) Hex string of the script public key\n"
            "    \"type\":\"str\",       (string) The type of the script public key (e.g. witness_v0_keyhash or witness_v0_scripthash)\n"
            "    \"reqSigs\": n,       (numeric) The required signatures (always 1)\n"
            "    \"addresses\": [      (json array of string) (always length 1)\n"
            "      \"address\"         (string) segwit address\n"
            "       ,...\n"
            "    ],\n"