Frame Containers lose their order when they are saved into an hdf5 file

For example I have a frame container going from 1 to 150 frames but when loaded back the frames are string sorted:

In [3]: fc = bob.bio.video.FrameContainer(bob.io.base.HDF5File(path))         
                                                                              
In [5]: for i, v, q in fc:                                                    
   ...:     print(i)                                                          
0                                                                             
1                                                                             
10                                                                            
100                                                                           
101                                                                           
102                                                                           
103                                                                           
104                                                                           
105                                                                           
106