Currently when viewing an old revision of an item that has 0 sources you still have the ability to expand the section.
The link / arrow to expand this section should just be removed if we are looking at an old revision with 0 sources
Version: master
Severity: normal
Prioritizing this "high" is odd in my opinion. This is barely a minor cosmetic issue. The arrows don't hurt. They simply don't do anything and the "0" does make it obvious why they don't do anything.
Yes, this clearly should be fixed. But in my opinion it should be low priority. Hiding the expand arrow doesn't save space. Barely saves time, if at all.