The proposals wait in a queue for the moderator(s) to handle them. It's impossible for me to predict in software when a proposal might be handled by a moderator.
So if you could edit a proposal, it's possible that the events could occur like this:
1) User submits a proposal.
2) Moderator opens the proposal queue and starts contemplating the proposals.
3) Original user goes into the queue, finds their proposal, clicks on edit and starts making changes.
4) While #3 is happening, the moderator clicks on approve.
5) Then original user clicks "Save my edits" but it fails because the proposal was already approved.
I try to avoid these kinds of conditions, especially since the need to edit a proposal is hopefully extremely rare. I could find a solution that works some or most of the time, but, honestly, I have other things that have a higher priority since this issue is so infrequently a problem.
