Bug#981558: grub2: Do not remove `/etc/default/grub` when purging grub-pc

[Paul Menzel]

Package: grub-pc
Version: 2.04-10
Severity: normal

Dear Debian folks,


Last year in December, I had installed a system with grub-pc, and then 
switched to grub-efi. Now purging *grub-pc*, and checking to *not* 
remove GRUB configuration files, at least `/etc/default/grub` was removed.

```
$ dpkg -l | grep "^rc"
rc  grub-pc                                  2.04-10 
     amd64        GRand Unified Bootloader, version 2 (PC/BIOS version)
rc  libccid                                  1.4.33-1 
     amd64        PC/SC driver for USB CCID smart card readers
rc  libpython3.8-minimal:amd64               3.8.7-1 
     amd64        Minimal subset of the Python language (version 3.8)
rc  python3.8-minimal                        3.8.7-1 
     amd64        Minimal subset of the Python language (version 3.8)
$ sudo apt purge grub-pc libccid libpython3.8-minimal python3.8-minimal
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
   grub-pc* libccid* libpython3.8-minimal* python3.8-minimal*
0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n]
(Reading database ... 218219 files and directories currently installed.)
Purging configuration files for libpython3.8-minimal:amd64 (3.8.7-1) ...
Purging configuration files for libccid (1.4.33-1) ...
Purging configuration files for grub-pc (2.04-10) ...
ucfr: Association belongs to grub-efi-amd64, not grub-pc
ucfr: Aborting
ucfr: Association belongs to grub-efi-amd64, not grub-pc
ucfr: Aborting
Purging configuration files for python3.8-minimal (3.8.7-1) ...
[master eacb665] committing changes in /etc made by "apt purge grub-pc 
libccid libpython3.8-minimal python3.8-minimal"
  Author: molgenit <molgenit at schuetz.fritz.box>
  5 files changed, 1600 deletions(-)
  delete mode 100644 default/grub
  delete mode 100644 libccid_Info.plist
  delete mode 100644 python3.8/sitecustomize.py
  delete mode 100644 reader.conf.d/libccidtwin
$ dpkg -l grub-ef*
Desired=Unknown/Install/Remove/Purge/Hold
| 
Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                  Version      Architecture Description
+++-=====================-============-============-=================================================================
ii  grub-efi              2.04-12      amd64        GRand Unified 
Bootloader, version 2 (dummy package)
ii  grub-efi-amd64        2.04-12      amd64        GRand Unified 
Bootloader, version 2 (EFI-AMD64 version)
ii  grub-efi-amd64-bin    2.04-12      amd64        GRand Unified 
Bootloader, version 2 (EFI-AMD64 modules)
ii  grub-efi-amd64-signed 1+2.04+12    amd64        GRand Unified 
Bootloader, version 2 (amd64 UEFI signed by Debian)
un  grub-efi-arm          <none>       <none>       (no description 
available)
un  grub-efi-arm64        <none>       <none>       (no description 
available)
un  grub-efi-ia32         <none>       <none>       (no description 
available)
un  grub-efi-ia64         <none>       <none>       (no description 
available)
```

Is that expected?


Kind regards,

Paul