See the diff: due to a bug in AWB, edit summary was with mismatching square brackets:
no 'of' between a month and a year per [[Wikipedia:Manual_of_Style_%28dates_and_numbers%29#Longer_periods|MOS]], added [[:Category:Uncategorized stubs|uncategori using [[Project:AutoWikiBrowser|AWB]]
it resulted in the following edit summary displayed: "no 'of' between a month and a year per MOS, added AWB", where AWB is linked to [[Category:Uncategorised stubs]]. This is completely diferent from how page text parser would handle such input.
Although we're working to fix edit summary trimming code in AWB, MediaWiki should also process summaries correctly.