Fix bugs in the COPY heap-insert batching patch.

Forgot to call RestoreBkpBlocks() in the redo-function, as pointed out by
Simon Riggs. In redo of a regular heap insert, it's taken care of in
heap_redo(), but this new record type uses the heap2 RM, and heap2_redo()
does not take care of that for you.

Also, failed to reset the vmbuffer and all_visibile_cleared local variables
after switching to a new buffer.

Author: hlinnaka

src/backend/access/heap/heapam.c

@@ -2088,9 +2088,6 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
 {
 	TransactionId xid = GetCurrentTransactionId();
 	HeapTuple  *heaptuples;
-	Buffer		buffer;
-	Buffer		vmbuffer = InvalidBuffer;
-	bool		all_visible_cleared = false;
 	int			i;
 	int			ndone;
 	char	   *scratch = NULL;
@@ -2128,6 +2125,9 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
 	ndone = 0;
 	while (ndone < ntuples)
 	{
+		Buffer		buffer;
+		Buffer		vmbuffer = InvalidBuffer;
+		bool		all_visible_cleared = false;
 		int nthispage;
 
 		/*
@@ -5038,6 +5038,13 @@ heap_xlog_multi_insert(XLogRecPtr lsn, XLogRecord *record)
 	int			i;
 	bool		isinit = (record->xl_info & XLOG_HEAP_INIT_PAGE) != 0;
 
+	/*
+	 * Insertion doesn't overwrite MVCC data, so no conflict processing is
+	 * required.
+	 */
+
+	RestoreBkpBlocks(lsn, record, false);
+
 	xlrec = (xl_heap_multi_insert *) recdata;
 	recdata += SizeOfHeapMultiInsert;