Since self.env.create always return db object now,
we can use this returned value instead of
self.env.clusters list.
It's a refactoring, so no bug or blueprint.
Change-Id: If7c84cb7124bcf08ef5ff110542012564190fae1
With plugins patching feature we cannot rely on
plugin version and plugin name to find the correct
plugin, because version can be changed after minor
plugin update, e.g. 1.0.0 -> 1.0.1.
Add migrations to replace plugin versions with
plugin ids. And use new code to enable/disable
plugins.
Change-Id: I44b04893a3b061fa31ce7612f8172ed0a58b1acd
Implements: blueprint plugins-security-fixes-delivery
Andreas Jaeger