Due to replacement of several info files (textutils, sh-utils, etc) by a single
"coreutils" info file which is part of the fileutils package.

Fix is probably to make sure updated packages have a pre- or post-
script/trigger to remove the info dir entries for the info files which are being
removed.

Manual fix is to delete bad entries from the info dir, then do a force upgrade
of the package to rerun the post script.

I think this is already fixed in the current release, isn't it?

No, this was never fixed.  There are still no scripts in textutils, sh-utils,
etc. to remove obsolete info dir entries when those packages are uninstalled.

It's only "fixed" in the sense that it's not an issue for new installations. 
It's still a problem for people upgrading from older releases in which
textutils, sh-utils, etc. had info dir entries which are now in the coreutils file.

The current coreutils package has:

preuninstall scriptlet (through /bin/sh):
if [ $1 = 0 ]; then
    [ -f /usr/share/info/coreutils.info.gz ] && \
      /sbin/install-info --delete /usr/share/info/coreutils.info.gz \
        /usr/share/info/dir || :
fi