Gentle reminder, do not forget, in rails 4

rake assets:clean

seems to work, but actually does nothing. That is not entirely true: it only cleans the old assets, leaving the three most recent versions of the assets intact. So it is a like a mild cleaning, a throw-away-the-garbage-clean, a bring-those-old-clothes-you-never-wear-to-the-thriftstore-clean.

But sometimes that does not cut it. Sometimes, don’t ask me why, building my assets does not seem to work, my code is just not being picked up. And then
you need to do use brute force cleaning (throw everything out). Run

rake assets:clobber

to actually clean the assets. The logic or meaning is lost on my me (clobber?), but this works.