I have made a edit to monobook.js on dewiki [0]. This change was not directly visible on my client. I have reload the page, logged off, cleared cache and login, nothing helps. After a time of 5 minutes it takes effect and I saw my suggested fix to the editsection placements on dewiki.
It is possible, that the recache on edit does not load the new script from master? Instead the old one goes into the cache. After 5 minutes (the default cache time for this) the new script is bundled into the cache (maybe also from slave, but no slave is more than 5 minutes behind master) and all will work.
This is a bad situation, when the first edit will introduce a javascript error and you recognize this after the 5 minutes, you fix to the javascript takes also 5 minutes to go to all clients. This means 5 minutes of javascript errors on the whole site, very bad.
[0] https://de.wikipedia.org/w/index.php?title=MediaWiki:Monobook.js&diff=prev&oldid=118091021
Version: 1.22.0
Severity: normal