All the Monticello GUI : track down version numbers to order stuff in the lists views everywhere.
The Metacello / Gofer stuff (Configurations, Baselines) also use version numbers.
One of the difficulty of switching will be the cohabitation of number-based systems (smalltalkhub) and SHA-based systems, especially when you do things like copying a version from a git repository to a smalltalkhub repository.
That's why I suggested to change the ordering relation to a partial order based on the property A is an ancestor of B -> B is before A.