RE: Fix resource leak in FindConflictTuple() retry path

[Hayato Kuroda (Fujitsu)]

Dear Nisha,

Not sure, should we release a buffer pin if should_refetch_tuple() returns true?
I referred heapam_tuple_lock()/heap_lock_tuple(), they pin a buffer via 
ReadBuffer()
and transfers to a slot via ExecStorePinnedBufferHeapTuple().

IIUC, ExecClearTuple() can release corresponding resources for the slot, so 
below
fix is enough.

```
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -268,7 +268,10 @@ retry:
                PopActiveSnapshot();
 
                if (should_refetch_tuple(res, &tmfd))
+               {
+                       ExecClearTuple(*conflictslot);
                        goto retry;
+               }
```

Best regards,
Hayato Kuroda
FUJITSU LIMITED