Display erroneous submodule commit ids in changes panel

Currently when a commit doesn't exist within a submodule, but a parent project is trying to point to it, "Could not determine submodule commit" is displayed. I would like the SHA ID also added to this message.

This will be useful for writing the ID on a lump of wood and repeatedly hitting a co-worker with.

Or most likely tracking down where and why this has appeared in the first place.