The problem appears to be that there are no .deb files provided (as all of the other arguments look valid). The execution of apt-listchanges is in line 225 of /usr/sbin/aptcron (on 17.10):
/usr/bin/apt-listchanges --which=both --headers -f text $DEBS
It would appear that $DEBS at this point is empty, rather than containing pathnames for the .debs to be listed. This would seem to point to a problem in lines 194 - 213, where DEBS is set.
OK, I dug into this a bit. I added the line
print(" apt-listchanges arguments: ", str(sys.argv))
as the first line of main in apt-listchanges. Next time apticron was called, it produced this:
--- ======= ======= ======= ======= ======= ======= ======= ======= ======= ==
apticron report [Tue, 27 Jun 2017 23:14:42 -0400]
=======
apticron has detected that some packages need upgrading on:
morannon. ln.benshome. net
[ 172.17.113.244 ]
The following packages are currently pending an upgrade:
bsdutils 1:2.29-1ubuntu2.1 g16a7302f- 0ubuntu1~ 17.04.1
grub-legacy-ec2 0.7.9-153-
libblkid1 2.29-1ubuntu2.1
libfdisk1 2.29-1ubuntu2.1
libmount1 2.29-1ubuntu2.1
libnss-resolve 232-21ubuntu5
libpam-systemd 232-21ubuntu5
libsmartcols1 2.29-1ubuntu2.1
libsystemd0 232-21ubuntu5
libudev1 232-21ubuntu5
libuuid1 2.29-1ubuntu2.1
mount 2.29-1ubuntu2.1
nplan 0.23~17.04.1
systemd 232-21ubuntu5
systemd-sysv 232-21ubuntu5
udev 232-21ubuntu5
util-linux 2.29-1ubuntu2.1
uuid-runtime 2.29-1ubuntu2.1
======= ======= ======= ======= ======= ======= ======= ======= ======= ======= ==
Package Details:
Usage: apt-listchanges [options] {--apt | filename.deb ...} bin/apt- listchanges' , '--which=both', '--headers', '-f', 'text']
apt-listchanges arguments: ['/usr/
---
The problem appears to be that there are no .deb files provided (as all of the other arguments look valid). The execution of apt-listchanges is in line 225 of /usr/sbin/aptcron (on 17.10):
/usr/bin/ apt-listchanges --which=both --headers -f text $DEBS
It would appear that $DEBS at this point is empty, rather than containing pathnames for the .debs to be listed. This would seem to point to a problem in lines 194 - 213, where DEBS is set.