They still happen occasionally on dist-upgrade, but recently I was running into them every week – still after one year.
Fix (other than noted on the shell):
# /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loaders > /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache