Comment 18 for bug 1692127

This also works for me on yakkety with apport version 2.20.3-0ubuntu8.6:

Setting up linux-image-4.8.0-58-generic (4.8.0-58.63) ...
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 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
update-initramfs: Generating /boot/initrd.img-4.8.0-58-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.8.0-58-generic /boot/vmlinuz-4.8.0-58-generic
/usr/sbin/grub-mkconfig: 15: /etc/default/grub: Syntax error: Unterminated quoted string
run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 2
Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/linux-image-4.8.0-58-generic.postinst line 1052.
dpkg: error processing package linux-image-4.8.0-58-generic (--configure):
 subprocess installed post-installation script returned error exit status 2