Last modified: 2014-09-17 11:18:40 UTC
Expected behavior: every entered category is added to the page. Actual behavior: all existing categories are removed, and only the entered ones are placed. Example: https://nl.wikipedia.org/w/index.php?title=NS_1200_(stoomlocomotief)&diff=39835503&oldid=39835472 Note: this is the case for both core and compat.
I think this is the expected behaviour. replaceCategoryLinks() is there since the first revision: https://www.mediawiki.org/wiki/Special:Code/pywikipedia/733
CC: Rob W.W. Hooft & Andre Engels who are listed as the initial copyright holders. If it is working as intended, the messages need to be clearer, and re-translated, but priority/severity of the bug can be reduced if it isnt a regression.