Remove references to priority that snuck back in in 870824e9.

The "priority" field should be appropriately marked as a "dummy"
value and noted that it is deprecated and will likely be removed.

src/rpc/client.cpp

@@ -112,7 +112,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "estimaterawfee", 0, "nblocks" },
     { "estimaterawfee", 1, "threshold" },
     { "estimaterawfee", 2, "horizon" },
-    { "prioritisetransaction", 1, "priority_delta" },
+    { "prioritisetransaction", 1, "dummy" },
     { "prioritisetransaction", 2, "fee_delta" },
     { "setban", 2, "bantime" },
     { "setban", 3, "absolute" },

src/rpc/mining.cpp

@@ -259,11 +259,12 @@ UniValue prioritisetransaction(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.size() != 3)
         throw std::runtime_error(
-            "prioritisetransaction <txid> <priority delta> <fee delta>\n"
+            "prioritisetransaction <txid> <dummy value> <fee delta>\n"
             "Accepts the transaction into mined blocks at a higher (or lower) priority\n"
             "\nArguments:\n"
             "1. \"txid\"       (string, required) The transaction id.\n"
-            "2. priority_delta (numeric, optional) Fee-independent priority adjustment. Not supported, so must be zero or null.\n"
+            "2. dummy          (numeric, optional) API-Compatibility for previous API. Must be zero or null.\n"
+            "                  DEPRECATED. For forward compatibility use named arguments and omit this parameter.\n"
             "3. fee_delta      (numeric, required) The fee value (in satoshis) to add (or subtract, if negative).\n"
             "                  The fee is not actually paid, only the algorithm for selecting transactions into a block\n"
             "                  considers the transaction as it would have paid a higher (or lower) fee.\n"
@@ -280,7 +281,7 @@ UniValue prioritisetransaction(const JSONRPCRequest& request)
     CAmount nAmount = request.params[2].get_int64();
 
     if (!(request.params[1].isNull() || request.params[1].get_real() == 0)) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, "Priority is not supported, and adjustment thereof must be zero.");
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Priority is no longer supported, dummy argument to prioritisetransaction must be 0.");
     }
 
     mempool.PrioritiseTransaction(hash, nAmount);
@@ -964,7 +965,7 @@ static const CRPCCommand commands[] =
   //  --------------------- ------------------------  -----------------------  ----------
     { "mining",             "getnetworkhashps",       &getnetworkhashps,       true,  {"nblocks","height"} },
     { "mining",             "getmininginfo",          &getmininginfo,          true,  {} },
-    { "mining",             "prioritisetransaction",  &prioritisetransaction,  true,  {"txid","priority_delta","fee_delta"} },
+    { "mining",             "prioritisetransaction",  &prioritisetransaction,  true,  {"txid","dummy","fee_delta"} },
     { "mining",             "getblocktemplate",       &getblocktemplate,       true,  {"template_request"} },
     { "mining",             "submitblock",            &submitblock,            true,  {"hexdata","parameters"} },