Lite and Puma construct scaffolds slightly differently

[axch]

Differences between Lite and Puma scaffold construction:

• re-traversing an aaa node updates the index assignment in Lite but not Puma
• re-traversing a drg node updates the index assignment and retraverses all the children (if the index assignment changed) in Lite but not Puma

Consequence: ordered foo inference should behave differently in the presence of dependencies that cross index boundaries (though regen will still regenerate everything it needs in order to compute what it wants to compute).

Do we care enough to synthesize a test case that exposes the difference?