Context: Point final qui part à la ligne and the 5 other talks linked there.
The line cuts can currently always happen before (resp. after) references, even if they are preceded (resp. followed) directly by a word, a punctuation mark or a non-breaking space.
This behaviour happens at least on enwiki and frwiki, with Safari, Chrome and Firefox. I don’t know non-French typography, but this is an error in French.
MediaWiki inserts a non-breaking space before the :, which is not respected.