Merge pull request #2018 from imaffe/affe-0520-fix-slotvalue

[ISSUE #1807] only increase hashSlotCount when using slot for the first time

store/src/main/java/org/apache/rocketmq/store/index/IndexFile.java

@@ -134,7 +134,9 @@ public class IndexFile {
                     this.indexHeader.setBeginTimestamp(storeTimestamp);
                 }
 
-                this.indexHeader.incHashSlotCount();
+                if (invalidIndex == slotValue) {
+                    this.indexHeader.incHashSlotCount();
+                }
                 this.indexHeader.incIndexCount();
                 this.indexHeader.setEndPhyOffset(phyOffset);
                 this.indexHeader.setEndTimestamp(storeTimestamp);