, this behavior is reproductible:
- user1 logs in and edits a new page (say test)
- user1 previews page, a draft gets created (inside data/cache/)
- user1 forgets about is edition or closes browser/tab
- user2 logs in and edits the page "test" (after lock has expired)
- user2 saves the content of the test page (ok)
- user1 comes back and edits test page: he is NOT prompted for draft edition, so his draft has been deleted and thus his initial, unsaved content it lost.
I would expect the draft created on step 2 for user1 not to be deleted when he edits the page at the last step and to be prompted for "draft edition".
Tested today with revision 147c74da3. The culprit lines are probably 205-207 from inc/common.php as they consider the draft created for user1 as stale after user2 has edited and saved the test file.