manpage of ubuntu-bug doesn't explain how to configure the primary browser to use

[Karl-Philipp Richter]

If multiple browsers are installed it's unclear which one is used and how to configure the primarily used browser and fallbacks.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: apport-gtk 2.20-0ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-12.28-generic 4.4.4
Uname: Linux 4.4.0-12-generic x86_64
NonfreeKernelModules: openafs
ApportLog:
 ERROR: apport (pid 14058) Thu Mar 17 16:47:38 2016: called for pid 13876, signal 5, core limit 0
 ERROR: apport (pid 14058) Thu Mar 17 16:47:38 2016: executable: /usr/sbin/synaptic (command line "/usr/sbin/synaptic")
 ERROR: apport (pid 14058) Thu Mar 17 16:47:38 2016: is_closing_session(): no DBUS_SESSION_BUS_ADDRESS in environment
 ERROR: apport (pid 14058) Thu Mar 17 16:47:38 2016: apport: report /var/crash/_usr_sbin_synaptic.0.crash already exists and unseen, doing nothing to avoid disk usage DoS
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
Date: Thu Mar 17 16:51:41 2016
InstallationDate: Installed on 2015-04-20 (332 days ago)
InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2)
PackageArchitecture: all
ProcEnviron:
 TERM=screen.xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: apport
UpgradeStatus: Upgraded to xenial on 2016-03-03 (13 days ago)