When we migrate a database, we migrate legacy SCMTool entrypoints,

creating a map of their class paths to names. Unfortunately, this code

regressed when we moved to the modern importlib-based entrypoints, as we

were accessing old attribute names.
This is a simple change that switches to the modern attributes, fixing

migration.

Verified this fixed a migration of an old database that had some

entrypoint-based SCMTools.