They did rename K-9. They just also have been making lots of improvements to K-9.

They still have two different apps, Thunderbird Mobile and K-9, but the only difference is the branding. All of the UI tweaks other than the icons and colours are in both apps. The functionality is identical. So other than not deleting K-9 it is a rename (I guess it is a hard link, not a rename).

>> making lots of improvements to K-9

Such as...?

That is just one of the downsides of the "stores" and basic package managers which do not have dependencies management where you can't do a transitional package.

Why is a transitional package necessary? Surely all of this isn't just to change the package name, which 99% of users won't see or care about.

I believe it is. Current k9mail and thunderbird are the exact same codebase and exact same dev team.