Okay, results of a quick look - the official repos seem to have evaporated from my sources.list. Putting them back by hand (nothing to loose by now) does not solve the issue as even though it DOES find the proper pre-installed-documentation-rx44 version in the repo if you try to apt-get it, it fails with a 401 error. I probably managed to mess up my sources (I do have a fair amount of custom repos) but it's still pretty uncommon for the apt-get update to succeed in finding a package and then and the install not to be able do download the package in question because of a 401... (unauthorized access)