Add explanatory comment

Author: mtodd

lib/net/ldap/connection.rb

@@ -541,6 +541,8 @@ def search(args = nil)
     # clean up message queue for this search
     messages = message_queue.delete(message_id)
 
+    # in the exceptional case some messages were *not* consumed from the queue,
+    # instrument the event but do not fail.
     unless messages.empty?
       instrument "search_messages_unread.net_ldap_connection",
                  message_id: message_id, messages: messages