Don't return the address of a P2SH of a P2SH.

Github-Pull: bitcoin#8845
Rebased-From: d51f182

src/rpc/rawtransaction.cpp

@@ -535,7 +535,7 @@ UniValue decodescript(const UniValue& params, bool fHelp)
             "     \"address\"     (string) bitcoin address\n"
             "     ,...\n"
             "  ],\n"
-            "  \"p2sh\",\"address\" (string) script address\n"
+            "  \"p2sh\",\"address\" (string) address of P2SH script wrapping this redeem script (not returned if the script is already a P2SH).\n"
             "}\n"
             "\nExamples:\n"
             + HelpExampleCli("decodescript", "\"hexstring\"")
@@ -554,7 +554,15 @@ UniValue decodescript(const UniValue& params, bool fHelp)
     }
     ScriptPubKeyToJSON(script, r, false);
 
-    r.push_back(Pair("p2sh", CBitcoinAddress(CScriptID(script)).ToString()));
+    UniValue type;
+    type = find_value(r, "type");
+
+    if (type.isStr() && type.get_str() != "scripthash") {
+        // P2SH cannot be wrapped in a P2SH. If this script is already a P2SH,
+        // don't return the address for a P2SH of the P2SH.
+        r.push_back(Pair("p2sh", CBitcoinAddress(CScriptID(script)).ToString()));
+    }
+
     return r;
 }