Version reverts on mod download failure

[TomatoCo]

I've had this happen on several mods, but I'm just going to give my steps to recreate for one of them.

First, I go for the Mk2 Expansion mod. This has a prerequisite of the KM_Gimbal mod. I already have that installed but it's not auto-detected.

This attempt to install failed, as you'd expect it to.

However! Next time you try to install, the Mk2 Expansion mod has gone from version 1.5 to 1.4.6.

Even with the manually installed copy of KM_Gimbal removed, attempts to download the Mk2 mod now fail because it tries to download a version that does not exist.

A workaround is to hit refresh, which brings the version of Mk2 back to 1.5.

EDIT: I just noticed that the other Mk2 mod visible in that list, Mk2 cockpit expansion, also had its version reverted.

[Postremus]

Maybe the registry removes the MK2 version 1.5 after the failed Installation from the availablemodules. This is a bad thing!

[Postremus]

I was able to reproduce it this way:

1. click on refresh
2. Close ckan while the refresh is still ongoing

[HebaruSan]

I've tested a lot of mod download failures recently as part of #3635, and I never saw this. Guessing it was fixed at some point.