Fix number of copying history items.

Author: akorotkov

contrib/pg_stat_wait/collector.c

@@ -148,10 +148,12 @@ ReallocHistory(History *observations, int count)
 	newitems = (HistoryItem *) palloc0(sizeof(HistoryItem) * count);
 
 	if (observations->wraparound)
-		copyCount = Min(observations->count, count);
+		copyCount = observations->count;
 	else
 		copyCount = observations->index;
 
+	copyCount = Min(copyCount, count);
+
 	i = 0;
 	j = observations->index;
 	while (i < copyCount)