fix sort bug

weed/filer2/filechunks.go

@@ -151,14 +151,17 @@ func mergeIntoVisibles(visibles, newVisibles []*visibleInterval, chunk *filer_pb
 	}
 	newVisibles = append(newVisibles, newV)
 
-	for i := len(newVisibles) - 1; i > 0; i-- {
-		if newV.start < newVisibles[i-1].start {
+	logPrintf("  append", newVisibles)
+
+	for i := len(newVisibles) - 1; i >= 0; i-- {
+		if i > 0 && newV.start < newVisibles[i-1].start {
 			newVisibles[i] = newVisibles[i-1]
 		} else {
 			newVisibles[i] = newV
 			break
 		}
 	}
+	logPrintf("  sorted", newVisibles)
 
 	return newVisibles
 }
@@ -175,9 +178,10 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 		t := visibles[:0]
 		visibles = newVislbles
 		newVislbles = t
-	}
 
-	logPrintf("visibles", visibles)
+		logPrintf("add", visibles)
+
+	}
 
 	return
 }