Verified shim-signed 1.27~16.04.1 on xenial:

Processing triggers for shared-mime-info (1.5-2ubuntu0.1) ...
Setting up libreoffice-core (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-base-core (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-calc (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-gtk (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-gnome (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-writer (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-draw (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-impress (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-ogltrans (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-pdfimport (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up python3-uno (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-math (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Setting up libreoffice-avmedia-backend-gstreamer (1:5.1.6~rc2-0ubuntu1~xenial1) ...
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160824-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for fontconfig (2.11.94-0ubuntu1.1) ...
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Processing triggers for initramfs-tools (0.122ubuntu8.8) ...
update-initramfs: Generating /boot/initrd.img-4.8.0-45-generic
Processing triggers for systemd (229-4ubuntu17) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for resolvconf (1.78ubuntu4) ...
Errors were encountered while processing:
 shim-signed
E:Sub-process /usr/bin/dpkg returned an error code (1)
Exception happened during upgrade.
Traceback (most recent call last):
  File "/usr/bin/unattended-upgrade", line 408, in cache_commit
    res = cache.commit(install_progress=iprogress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 519, in commit
    raise SystemError("installArchives() failed")
SystemError: installArchives() failed
Installing the upgrades failed!
error message: 'installArchives() failed'
dpkg returned a error! See '/var/log/unattended-upgrades/unattended-upgrades-dpkg.log' for details
marking snap-confine for remove
Packages that are auto removed: 'snap-confine'
(Reading database ... 207712 files and directories currently installed.)
Removing snap-confine (2.23.1) ...
Setting up shim-signed (1.27~16.04.1+0.9+1474479173.6c180c6-1ubuntu1) ...
Installing for x86_64-efi platform.
Installation finished. No error reported.
Running in non-interactive mode, doing nothing.
dpkg: error processing package shim-signed (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 shim-signed
E:Sub-process /usr/bin/dpkg returned an error code (1)
Exception happened during upgrade.
Traceback (most recent call last):
  File "/usr/bin/unattended-upgrade", line 408, in cache_commit
    res = cache.commit(install_progress=iprogress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 519, in commit
    raise SystemError("installArchives() failed")
SystemError: installArchives() failed
Auto-removing the packages failed!
Error message: 'installArchives() failed'
dpkg returned an error! See '/var/log/unattended-upgrades/unattended-upgrades-dpkg.log' for details
InstCount=0 DelCount=1 BrokenCount=0
Extracting content from '/var/log/unattended-upgrades/unattended-upgrades-dpkg.log' since '2017-03-31 14:08:17'