see Trésor de la Langue Française s.v. charrette

That's weird. If you follow the link from the site linked in the Wikipedia article, they give a different origin for charrette.
 Quote:
This use of the term is said to originate from the École des Beaux Arts in Paris during the 19th century, where proctors circulated a cart, or "charrette", to collect final drawings while students frantically put finishing touches on their work.
Both Wikipedia and the OED cite the Trésor de la Langue Française.
 Quote:
P. réf. à la coutume des élèves d'archit. qui, le jour de l'exposition, chargeaient leurs projets sur une charrette tirée par le plus jeune de l'atelier.
This is one idiomatic meaning, but it retains its primary, unchanged meaning of cart, too. The citation is from the 1960s, and no mention is made of the École des Beaux Arts. So, rather than losing its meaning (has any word done that?), it's gained another one (many have done that!).


Ceci n'est pas un seing.