This wasn't present in the previous version of Pagure IIRC.
In the new Pagure, it is possible to get the preview and edit tabs on issues/etc. into an inconsistent state.
preview
edit
See: https://cipherboy.com/i/23015-29051.png / https://cipherboy.com/i/20553-6533.png
I believe this can be reproduced in Chromium by clicking edit when you're already in the edit tab. :)
This is fixed in PR#4018.
Commit 4d6c4120 fixes this issue
Metadata Update from @pingou: - Issue set to the milestone: 5.2 - Issue tagged with: JS, UI, bug