Comment 0 for bug 1796193

I'm trying to do some automated testing that involved upgrading a system from xenial to bionic, so I need it to not ask for user input.

Before running do-release-upgrade, the system got a fresh dist-upgrade and reboot.

To avoid interactive responses, I'm using:
$ sudo do-release-upgrade -d -f DistUpgradeViewNonInteractive

Part way through the upgrade, I do get prompted for something though:
Preparing to unpack .../apt_1.6.3ubuntu0.1_amd64.deb ...

Unpacking apt (1.6.3ubuntu0.1) over (1.2.27) ...

Processing triggers for libc-bin (2.27-3ubuntu1) ...

/sbin/ldconfig.real: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf.d/x86_64-linux-gnu_EGL.conf: No such file or directory

/sbin/ldconfig.real: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf: No such file or directory

Setting up apt (1.6.3ubuntu0.1) ...

Installing new version of config file /etc/apt/apt.conf.d/01autoremove ...

Configuration file '/etc/cron.daily/apt-compat'

 ==> Deleted (by you or by a script) since installation.

 ==> Package distributor has shipped an updated version.

   What would you like to do about it ? Your options are:

    Y or I : install the package maintainer's version

    N or O : keep your currently-installed version

      D : show the differences between the versions

      Z : start a shell to examine the situation

 The default action is to keep your current version.

Comparing the sha1 of apt-compat before the upgrade to another xenial system that has been unmodified, they are the same:

In /var/log/dist-upgrade/main.log, I also found this:
2018-10-04 14:20:24,575 WARNING got a conffile-prompt from dpkg for file: '/etc/cron.daily/apt-compat'
2018-10-04 14:20:29,580 ERROR error 'a bytes-like object is required, not 'str'' when trying to write to the conffile