bitcoin-tx: Reject + sign in locktime

test/util/data/bitcoin-util-test.json

@@ -132,6 +132,12 @@
     "output_cmp": "tt-locktime317000-out.json",
     "description": "Adds an nlocktime to a transaction (output in json)"
   },
+  { "exec": "./bitcoin-tx",
+    "args": ["-create", "locktime=+317"],
+    "return_code": 1,
+    "error_txt": "error: Invalid TX locktime requested",
+    "description": "Tests the check for invalid locktime value"
+  },
   { "exec": "./bitcoin-tx",
     "args": ["-create", "locktime=317000foo"],
     "return_code": 1,