This is not actually a version update, yet it is. The story: on the
ocamlcore forge, the file downloaded doesn't depend on the filename, but
on the number at the end of the URL. I forgot to update that last time
around, so it was still downloading (and hence installing) 2.18.2 at that
point. I have corrected this now - the version being installed is
definitely 2.18.3. Have bumped the PKGREVISION to make sure things get
reinstalled.

(jaapb)