Jakub Narebski [off-list ref] writes:
By the way, in todo branch, in Subpro.txt, there is talk about adding
link to submodule trees in _commit object_... well link to submodule tree
or commit, with the "mount point".
That was shot down by Linus and I agree with him. "bind" was a
bad idea because binding of a particular subproject commit into
a tree is a property of the tree, not one of the commits that
happen to have that tree.