THRIFT-4129: Fix fd leak when failing to dispatch new connections
Client: C++

This closes #1210
diff --git a/lib/cpp/src/thrift/server/TNonblockingServer.cpp b/lib/cpp/src/thrift/server/TNonblockingServer.cpp
index d4418bd..2cf64f8 100644
--- a/lib/cpp/src/thrift/server/TNonblockingServer.cpp
+++ b/lib/cpp/src/thrift/server/TNonblockingServer.cpp
@@ -1004,7 +1004,7 @@
     } else {
       if (!clientConnection->notifyIOThread()) {
         GlobalOutput.perror("[ERROR] notifyIOThread failed on fresh connection, closing", errno);
-        returnConnection(clientConnection);
+        clientConnection->close();
       }
     }