Revert "Closes #1680, temporary fix for rpc deadlock inherited from upstream."

This reverts commit f4404d7b5b.

src/rpcserver.cpp

@@ -1023,15 +1023,9 @@ void ServiceConnection(AcceptedConnection *conn)
         // Read HTTP message headers and body
         ReadHTTPMessage(conn->stream(), mapHeaders, strRequest, nProto, MAX_SIZE);
 
-        // TODO #1856: Re-enable support for persistent connections.
-        // We have disabled support for HTTP Keep-Alive until resolution of #1680, upstream rpc deadlock.
-        // Close connection immediately.
-        fRun = false;
-        /*
         // HTTP Keep-Alive is false; close connection immediately
         if ((mapHeaders["connection"] == "close") || (!GetBoolArg("-rpckeepalive", true)))
             fRun = false;
-        */
 
         // Process via JSON-RPC API
         if (strURI == "/") {