apport-bug unable to init server, dumps core

After upgrading to 17.10, apport-bug fails with the follow error:

# apport-bug
No protocol specified
Unable to init server: Could not connect: Connection refused
No protocol specified
Unable to init server: Could not connect: Connection refused
Segmentation fault (core dumped)

Calling apport-cli directly works just fine. The problem seems to be a general Xwayland permission issue, since nothing can connect to the display server if sudo/su is used:

$ sudo xclock
No protocol specified
Error: Can't open display: :0
$ xauth list
xauth: file /home/user/.Xauthority does not exist

If that's the way things are going to be in Ubuntu from now on, we need to make apport-bug a bit smarter in the way it decides whether to use the GUI version or not.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: apport 2.20.7-0ubuntu3
ProcVersionSignature: Ubuntu 4.13.0-15.16-generic 4.13.4
Uname: Linux 4.13.0-15-generic x86_64
ApportVersion: 2.20.7-0ubuntu3
Architecture: amd64
CrashReports: 640:0:119:7137742:2017-10-13 09:46:22.546417474 +1100:2017-10-13 09:46:23.546417474 +1100:/var/crash/_usr_share_apport_apport-gtk.0.crash
Date: Fri Oct 13 09:49:17 2017
InstallationDate: Installed on 2016-12-02 (313 days ago)
InstallationMedia: Ubuntu-GNOME 16.10 "Yakkety Yak" - Release amd64 (20161012.1)
PackageArchitecture: all
ProcEnviron:
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
 TERM=xterm-256color
 LANGUAGE=en_AU:en
 PATH=(custom, no user)
SourcePackage: apport
UpgradeStatus: Upgraded to artful on 2017-10-12 (0 days ago)