Remove bad retain.

Author: JoshRosen

network/common/src/main/java/org/apache/spark/network/protocol/MessageEncoder.java

@@ -49,11 +49,8 @@ public void encode(ChannelHandlerContext ctx, Message in, List<Object> out) thro
 
     // If the message has a body, take it out to enable zero-copy transfer for the payload.
     if (in.body() != null) {
-      bodyLength = in.body().size();
-      if (bodyLength > 0) {
-        in.body().retain();
-      }
       try {
+        bodyLength = in.body().size();
         body = in.body().convertToNetty();
         isBodyInFrame = in.isBodyInFrame();
       } catch (Exception e) {

network/common/src/test/java/org/apache/spark/network/TestManagedBuffer.java

@@ -44,7 +44,7 @@ public TestManagedBuffer(int len) {
     for (int i = 0; i < len; i ++) {
       byteArray[i] = (byte) i;
     }
-    this.underlying = new NettyManagedBuffer(Unpooled.wrappedBuffer(byteArray));
+    this.underlying = new NettyManagedBuffer(Unpooled.wrappedBuffer(byteArray).retain());
   }