Last modified: 2014-05-15 22:49:46 UTC
This can be reproduced at https://wikitech.wikimedia.org/wiki/Sandbox , for instance. I think this is because wikitech has a custom domain (not sure why, and I need to find the config). The domain and path have to be set exactly the same when clearing the cookie.
The symptom is that it shows the post-edit message every time you visit the page, until it expires.
Change 120806 had a related patch set uploaded by Phuedx: [WIP] Add the mw.cookie module https://gerrit.wikimedia.org/r/120806
Change 122423 had a related patch set uploaded by Phuedx: Delete the post-edit cookie using the correct domain https://gerrit.wikimedia.org/r/122423
And merged. (Gerrit Notification Bot is currently down.)