Clean up the DEP17 dpkg diversions

[Simon Chopin]

For the DEP17 effort, we've introduced a number of dpkg diversions of the form $foo -> $foo.usr-is-merged, ahead of Debian. They've done since their own transition, and the diversions they added are much less numerous and much more discreet (only for "multiarch" dirs such as /lib64 and /lib32, and using /.$foo.usr-is-merged which is way less invasive).

When merging glibc and base-files, where those diversions are added in the preinsts, we should take care of cleaning up our old diversions as well as whatever still clutter the filesystem.

[Michael Biebl (mbiebl)]

Speaking of which, is the following expected (a system that has recently been upgraded to 24.04):

```
# ls -la /
insgesamt 84
drwxr-xr-x 21 root root 4096 Jun 24 23:49 .
drwxr-xr-x 21 root root 4096 Jun 24 23:49 ..
lrwxrwxrwx 1 root root 7 Jan 7 00:36 bin -> usr/bin
drwxr-xr-x 2 root root 4096 Apr 8 16:46 bin.usr-is-merged
drwxr-xr-x 4 root root 4096 Jun 14 12:19 boot
drwxr-xr-x 19 root root 5040 Jun 24 23:46 dev
drwxr-xr-x 148 root root 12288 Jun 24 23:48 etc
drwxr-xr-x 3 root root 4096 Jan 19 17:12 home
lrwxrwxrwx 1 root root 7 Jan 7 00:36 lib -> usr/lib
lrwxrwxrwx 1 root root 9 Jan 7 00:36 lib32 -> usr/lib32
lrwxrwxrwx 1 root root 9 Jan 7 00:36 lib64 -> usr/lib64
drwxr-xr-x 2 root root 4096 Apr 8 16:46 lib.usr-is-merged
lrwxrwxrwx 1 root root 10 Jan 7 00:36 libx32 -> usr/libx32
drwx------ 2 root root 16384 Jan 6 23:19 lost+found
drwxr-xr-x 3 root root 4096 Jan 11 21:44 media
drwxr-xr-x 6 root root 4096 Jun 2 09:54 mnt
drwxr-xr-x 3 root root 4096 Jan 7 21:14 opt
dr-xr-xr-x 433 root root 0 Jun 24 23:45 proc
drwx------ 9 root root 4096 Jun 14 12:02 root
drwxr-xr-x 35 root root 860 Jun 24 23:48 run
lrwxrwxrwx 1 root root 8 Jan 7 00:36 sbin -> usr/sbin
drwxr-xr-x 2 root root 4096 Apr 8 16:46 sbin.usr-is-merged
drwxr-xr-x 2 root root 4096 Feb 28 01:24 srv
dr-xr-xr-x 13 root root 0 Jun 24 23:48 sys
drwxrwxrwt 20 root root 520 Jun 24 23:51 tmp
drwxr-xr-x 14 root root 4096 Aug 8 2023 usr
drwxr-xr-x 14 root root 4096 Jun 14 12:23 var
```
Specifically those $foo.usr-is-merged directories?

[Julian Andres Klode (juliank)]

Yes sure, this is expected, that's the DEP17 M4 mitigations

[Launchpad Janitor (janitor)]

This bug was fixed in the package base-files - 13.3ubuntu2

---------------
base-files (13.3ubuntu2) oracular; urgency=medium

  * Temporarily revert the Breaks on libc6 to avoid archive breakage

base-files (13.3ubuntu1) oracular; urgency=medium

  * Merge with Debian unstable. Remaining changes:
    - Add /etc/lsb-release file.
    - /etc/issue{,.net}, /etc/{lsb,os}-release: Welcome to ATTRIBUTE ANIMAL!
    - Install locale-check command to /usr/bin and invoke it from
      /etc/profile.d/01-locale-fix.sh to ensure locale related environment
      variables are set to valid values.
    - Include systemd service to check the motd.ubuntu.com service
    - Various bashrc extensions.
    - Do not install /usr/local dirs with staff group writeability.
    - Add default /etc/networks file.
    - Remove the upgrade-available flag on package upgrade.
    - Restore order line in /etc/host.conf with a comment.
    - Build a motd-news-config package.
    - Add update-motd scripts.
    - etc/legal: legal notice for Ubuntu
    - Depend on libcrypt1 (>= 1:4.4.10-10ubuntu3).
    - set a LOGO=ubuntu-logo key which is part of the specification,
      install ubuntu-logo/-text/-text-dark icons
    Dropped, superseded by Debian changes:
    - install aliasing symlinks for merged-/usr DEP17
    - Include debhelper token in postinst.
    Dropped, obsolete:
    - Drop lsb-release-udeb package.

  [ Julian Andreas Klode ]
  * Rename protective diversions to include a leading dot as Debian does.
    (LP: #2070061)

base-files (13.3) unstable; urgency=medium

  [ Helmut Grohne ]
  * DEP17: Install /usr-merge aliasing symlinks. Closes: #1064459.

base-files (13.2) unstable; urgency=medium

  * Document that /etc/profile is not a conffile anymore. Closes: #868095.
  * Use a regexp to source files in /etc/profile.d. The behaviour should now be
    well defined and consistent. Closes: #885414, #1069279.
  * Add NEWS.Debian entry for the above.
  * Document that the default umask is defined in /etc/login.defs. Closes: #983606.
  * Add #DEBHELPER# token to postinst to make lintian happy.
  * Make binary package to be git-reproducible.

 -- Simon Chopin <email address hidden> Fri, 28 Jun 2024 09:52:47 +0200