Can't migrate from custom to main without reinstall

[kal]

This issue makes it harder for 3pp to migrate and become main repo plugins.

Steps to Recreate

1. User installs custom repo plugin.
2. Developer publishes the plugin using same internal name on main repo with higher version.

Expected

• User can update to latest and be switched to main repo.

Actual

• User can't update and needs to uninstall and reinstall the main repo version.