MB-48292: Don't clear buffer message when bytes received by libuv is 0

Change-Id: I1600e1d398e1d76a132cfe4e25bd10ef1a5aa8d5
Reviewed-on: http://review.couchbase.org/c/eventing/+/159865
Reviewed-by: Jeelan Basha Poola <jeelan.poola@couchbase.com>
Reviewed-by: CI Bot
Tested-by: <ankit.prabhu@couchbase.com>
(cherry picked from commit 9986391)
Reviewed-on: http://review.couchbase.org/c/eventing/+/164408
Well-Formed: Restriction Checker
Tested-by: Jeelan Basha Poola <jeelan.poola@couchbase.com>

v8_consumer/src/client.cc

@@ -321,16 +321,16 @@ void AppWorker::OnRead(uv_stream_t *stream, ssize_t nread,
                        const uv_buf_t *buf) {
   if (nread > 0) {
     AppWorker::GetAppWorker()->ParseValidChunk(stream, nread, buf->base);
-  } else if (nread == 0) {
-    next_message_.clear();
-  } else {
+  } else if (nread < 0) {
     if (nread != UV_EOF) {
       LOG(logError) << "Read error, err code: " << uv_err_name(nread)
                     << std::endl;
     }
-    AppWorker::GetAppWorker()->ParseValidChunk(stream, next_message_.length(),
-                                               next_message_.c_str());
+
+    std::string old_message_ = next_message_;
     next_message_.clear();
+    AppWorker::GetAppWorker()->ParseValidChunk(stream, old_message_.length(),
+                                               old_message_.c_str());
     uv_read_stop(stream);
   }
 }