x11-utils needs to depend on xbitmaps or xmessage throws noisy error on terminal output or over mta from cron jobs

Noise as seen through MTA to smtp.gmail.com from Cron Daemon:

From: root <***me***@gmail.com>
X-Google-Original-From: root (Cron Daemon)
Date: Wed, 17 Feb 2016 14:06:04 -0600
To: chris
Subject: Cron <chris@***$HOSTNAME***> ~chris/.BATTERY_LOW_WARNING.sh
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/home/chris>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=chris>

[[ xmessage attempts output here ]] Warning: Cannot convert string "vlines2" to type Pixmap

*** END OF BUG DESCRIPTION ***

chris@CKR-2:~$ lsb_release -rd
Description: Ubuntu 15.10
Release: 15.10

chris@CKR-2:~$ apt-cache policy x11-utils
x11-utils:
  Installed: 7.7+3
  Candidate: 7.7+3
  Version table:
 *** 7.7+3 0
        500 http://us.archive.ubuntu.com/ubuntu/ wily/main amd64 Packages
        100 /var/lib/dpkg/status

I expected the installation of x11-utils to pull _all_ required dependencies to avoid spurious errors/outputs.

I had to hunt down a 10-year-old bug-report on this same issue, which was more of a work-a-round for another package, than the fix truly needed. See: https://bugs.launchpad.net/ubuntu/+source/xterm/+bug/67435

BTW: This is on a minimal ubuntu-server install without: xterm or x11-apps

Post-install packages added:

* LAPTOP-SERVER: sudo apt-get install anacron apt-file arandr \
avahi-utils chromium-browser conky cups dmz-cursor-theme \
ecryptfs-utils fonts-noto-hinted gnome-screenshot gnome-terminal \
hplip-gui hsetroot libavcodec-extra libav-tools-links lightdm \
lightdm-gtk-greeter light-locker logwatch mpv msmtp-mta nautilus \
openbox policykit-desktop-privileges rfkill simple-scan \
smart-notifier transmission-gtk unity-control-center unzip \
update-manager upower va-driver-all xbacklight