Bug#849532: flash-kernel does not remove dtb backups

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

Package: flash-kernel
Version: 3.72
Severity: normal

Dear Maintainer,

when a Linux kernel is installed flash-kernel creates a dtb backup file.

This file is not removed when the Linux kernel is remove. E.g.

sudo apt-get remove linux-image-4.8.0-1-armmp
left file
/boot/dtbs/4.8.0-1-armmp/imx6q-wandboard-revb1.dtb.bak

As it is flash-kernel that creates both the
/boot/dtbs/$version/$model.dtb
as well as the
/boot/dtbs/$version/$model.dtb.bak
files it should also take care of removing them fully.

The .bak file should not be created on the first install of a Linux kernel.

Best regards

Heinrich Schuchardt

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: armhf (armv7l)

Kernel: Linux 4.8.0-2-armmp (SMP w/4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to en_US.UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages flash-kernel depends on:
ii  debconf [debconf-2.0]  1.5.59
ii  devio                  1.2-1.2
ii  initramfs-tools        0.126
ii  linux-base             4.5
ii  mtd-utils              1:2.0.0~rc1-1
ii  ucf                    3.0036

Versions of packages flash-kernel recommends:
ii  u-boot-tools  2016.11+dfsg1-1

flash-kernel suggests no packages.

-- debconf information:
  flash-kernel/linux_cmdline: quiet