dpkg-reconfigure locales does not add locale to /etc/default/locale

[HankB]

1) Install Ubuntu 18.04 via debbootstrap (following instructions at https://github.com/zfsonlinux/zfs/wiki/Ubuntu-18.04-Root-on-ZFS)
2) install ubuntu-desktop (`apt install ubuntu0desktop`)
3) reboot.
Content of /etc/default/locale is one line "LANG=en_US"
Consequence of this is that an xterm will not start resulting in following errors in /var/log/syslog
Dec 12 13:37:52 saugage gnome-shell[12845]: Received error from DBus search provider org.gnome.Terminal.desktop: Gio.IOErrorEnum: Timeout was reached
Dec 12 13:37:57 saugage gnome-terminal.desktop[14431]: # Error constructing proxy for org.gnome.Terminal:/org/gnome/Terminal/Factory0: Error calling StartServiceByName for org.gnome.Terminal: Timeout was reached

Tracking down the cause of the error indicated missing entry in /etc/default/locale. Adding the following solved problem:
  hbarta@saugage:~$ cat /etc/default/locale
  # File generated by update-locale
  LANG=en_US
  LC_ALL="en_US.UTF-8"

hbarta@saugage:/var/log$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04

When I ran `dpkg-reconfigure locales` I selected en_US for the default locale.

Possibly related to bug #1598326

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: locales 2.27-3ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-42.45-generic 4.15.18
Uname: Linux 4.15.0-42-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Wed Dec 12 14:06:53 2018
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US
 SHELL=/bin/bash
SourcePackage: glibc
UpgradeStatus: No upgrade log present (probably fresh install)