During kernel upgrade, /usr/sbin/dkms falsely reports that initrd.img won't be created

Ubuntu release
==============

Description: Ubuntu 16.04.1 LTS
Release: 16.04

Version of package
==================

dkms:
  Installed: 2.2.0.3-2ubuntu11.3
  Candidate: 2.2.0.3-2ubuntu11.3
  Version table:
 *** 2.2.0.3-2ubuntu11.3 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main i386 Packages
        100 /var/lib/dpkg/status
     2.2.0.3-2ubuntu11 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu xenial/main i386 Packages

The problem
===========

When setting up `linux-image-4.4.0-53-generic`, the following warning appears three times:

    : Unable to find an initial ram disk that I know how to handle.
    Will not try to make an initrd.

However, when setting up `linux-image-extra-4.4.0-53-generic`, the following message appears:

    update-initramfs: Generating /boot/initrd.img-4.4.0-53-generic

The text "Unable to find an initial ram disk" appears in `/usr/sbin/dkms`, though it may appear elsewhere.

What should happen
==================

The warning message should not appear.

Messages when setting up the two packages
=========================================

Setting up linux-image-4.4.0-53-generic (4.4.0-53.74) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/dkms 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
: Unable to find an initial ram disk that I know how to handle.
Will not try to make an initrd.
: Unable to find an initial ram disk that I know how to handle.
Will not try to make an initrd.
: Unable to find an initial ram disk that I know how to handle.
Will not try to make an initrd.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-53-generic
Found initrd image: /boot/initrd.img-4.4.0-53-generic
Found linux image: /boot/vmlinuz-4.4.0-51-generic
Found initrd image: /boot/initrd.img-4.4.0-51-generic
Found linux image: /boot/vmlinuz-4.4.0-47-generic
Found initrd image: /boot/initrd.img-4.4.0-47-generic
Adding boot menu entry for EFI firmware configuration
done
Setting up linux-image-extra-4.4.0-53-generic (4.4.0-53.74) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/dkms 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-53-generic /boot/vmlinuz-4.4.0-53-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-53-generic
Found initrd image: /boot/initrd.img-4.4.0-53-generic
Found linux image: /boot/vmlinuz-4.4.0-51-generic
Found initrd image: /boot/initrd.img-4.4.0-51-generic
Found linux image: /boot/vmlinuz-4.4.0-47-generic
Found initrd image: /boot/initrd.img-4.4.0-47-generic
Adding boot menu entry for EFI firmware configuration
done

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: dkms 2.2.0.3-2ubuntu11.3
ProcVersionSignature: Ubuntu 4.4.0-53.74-generic 4.4.30
Uname: Linux 4.4.0-53-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Dec 5 19:30:51 2016
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-xenial-amd64-20160624-2
EcryptfsInUse: Yes
InstallationDate: Installed on 2016-11-01 (34 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
PackageArchitecture: all
SourcePackage: dkms
UpgradeStatus: No upgrade log present (probably fresh install)