A bug about SYSU_triplet_dataset

```python
        for id in sorted(self.ids):
            self.all_files.extend(self.files_rgb[id])
            #self.rgb_files.extend(self.files_rgb[id])
            self.all_files.extend(self.files_rgb[id])
            #self.ir_files.extend(self.files_ir[id]) 
```

Why both step add files_rgb?  