### Describe the issue

### Can you reliably reproduce the issue?
#### If so, please list the steps to reproduce below:
1. Follow the steps in https://gist.github.com/gavinandresen/3966071

### Expected behaviour
The first `signrawtransaction` command should be successful and return a partially signed transaction that can be sent to the other cosigners for signing.

### Actual behaviour
Instead `signrawtransaction` fails and does not return a partially signed transaction.

### What version of bitcoin-core are you using?
This was reported for 0.14.0. However we have determined that it affects 0.11.1 and later, and likely 0.11.0. It does not affect 0.10.3.

It appears that the bug is caused by [this `VerifyScript` call](https://github.com/bitcoin/bitcoin/blob/master/src/rpc/rawtransaction.cpp#L849) which was introduced in 8ac2a4e1788426329b842eea7121b8eac7875c76 which has been a part of all versions since 0.11.0rc1.

See also: https://bitcointalk.org/index.php?topic=1823847.msg18164848#msg18164848
"keys that, if given, will be the only keys used to sign the transaction.\n"
#ifdef ENABLE_WALLET
            + HelpRequiringPassphrase(pwallet) + "\n"
#endif
            "\nArguments:\n"
            "1. \"hexstring\"     (string, required) The transaction hex string\n"
            "2. \"prevtxs\"       (string, optional) An json array of previous dependent transaction outputs\n"
            "     [               (json array of json objects, or 'null' if none provided)\n"
            "       {\n"
            "         \"txid\":\"id\",             (string, required) The transaction id\n"
            "         \"vout\":n,                  (numeric, required) The output number\n"
            "         \"scriptPubKey\": \"hex\",   (string, required) script key\n"
            "         \"redeemScript\": \"hex\",   (string, required for P2SH or P2WSH) redeem script\n"
            "         \"amount\": value            (numeric, required) The amount spent\n"
            "       }\n"
            "       ,...\n"
            "    ]\n"
            "3. \"privkeys\"     (string, optional) A json array of base58-encoded private keys for signing\n"
            "    [                  (json array of strings, or 'null' if none provided)\n"
            "      \"privatekey\"   (string) private key in base58-encoding\n"
            "      ,...\n"
            "    ]\n"
            "4. \"sighashtype\"     (string, optional, default=ALL) The signature hash type. Must be one of\n"
            "       \"ALL\"\n"
            "       \"NONE\"\n"
            "       \"SINGLE\"\n"
            "       \"ALL|ANYONECANPAY\"\n"
            "       \"NONE|ANYONECANPAY\"\n"
            "       \"SINGLE|ANYONECANPAY\"\n"
            "\nResult:\n"