AutoGrouper is broken for JPEG/RAW pairs

In darktable I import both JPEG and RAW into the library. (It is sometimes convenient to compare JPEGs and RAW developments that way.)

Now when I apply Auto group to a selection, the following happens:

• For the first pair of images of a group, both JPEG and RAW are included, with the first RAW being the group leader. This is expected and what I hoped would happen.
• For the following images, up to the gap in time signalling the end of the group:
  • The RAW images get added to the group
  • The JPEG images do not get added and remain group-less.

I would like to have all JPEGs and RAWs added to the group.

If I have time I might look into this myself, but that is not likely in the next few weeks. We'll see.

If you need them I can provide a sample burst of images or two.

Start by reproducing Auto group on a selection containing JPEG/RAW pairs and then locate the Auto group entry point in the lua-scripts repository. Compare how the first pair and following images are handled; done means every JPEG and RAW in the time-bounded group is included.