Displaying diffs between two versions of an MR doesn't seem to be working properly
Summary
I have a WIP MR where I'm using lots of force pushes. the UI shows I have 9 ("latest" + 8) versions. Displaying the diff between version 8 and version 7 shows the diff against master.
I've just noticed that the versions 1..8 don't have ticks against them in the second version selector. Maybe that means they can't be diffed against? But why?
Greying them out and disabling clicks might be more appropriate than absence of a tick if that's the case.
Steps to reproduce
Expected behavior
Should see single-digit numbers of hunks, or at least a notification or error saying the diff couldn't be generated, here's master instead.
Actual behavior
The diff against master is displayed with no error text