Comment 16 for bug 1269177

The new version in zesty-proposed resolves the issue for me.

bdmurray@clean-zesty-amd64:~$ sudo apt-get install unattended-upgrades
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.10.0-19 linux-headers-4.10.0-19-generic linux-image-4.10.0-19-generic linux-image-extra-4.10.0-19-generic
Use 'sudo apt autoremove' to remove them.
Suggested packages:
  bsd-mailx mail-transport-agent needrestart
The following packages will be upgraded:
  unattended-upgrades
1 upgraded, 0 newly installed, 0 to remove and 43 not upgraded.
Need to get 34.7 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://192.168.10.7/ubuntu zesty-proposed/main amd64 unattended-upgrades all 0.93.1ubuntu2.4 [34.7 kB]
Fetched 34.7 kB in 0s (1,556 kB/s)
Preconfiguring packages ...
(Reading database ... 259925 files and directories currently installed.)
Preparing to unpack .../unattended-upgrades_0.93.1ubuntu2.4_all.deb ...
Unpacking unattended-upgrades (0.93.1ubuntu2.4) over (0.93.1ubuntu2.3) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for systemd (232-21ubuntu7.1) ...
Setting up unattended-upgrades (0.93.1ubuntu2.4) ...
Processing triggers for man-db (2.7.6.1-2) ...
bdmurray@clean-zesty-amd64:~$ sudo unattended-upgrades --dry-run
bdmurray@clean-zesty-amd64:~$ sudo touch /var/run/reboot-required
bdmurray@clean-zesty-amd64:~$ sudo unattended-upgrades --dry-run
bdmurray@clean-zesty-amd64:~$