Refactored the progress-related scripts (import, install, upgrade) in 4.0.9 to prevent a related issue where multiple old versions that were only upgraded partly could force re-execution of platform-specific steps from those versions (which could lead to corruption). The refactor should ensure that progress is only counted towards the related versions without also ignoring progress on other steps that occur under specific platform versions.
An added bonus is that the design of the progress scripts is now easier for a human to understand.