ubuntu-bug fails to open launchpad page when default browser is chromium

[nicola dmt]

Release: Ubuntu 16.04 LTS (pre-release daily build)
Hardware: Dell Inspiron 15 5000 Series (Intel(R)) - 5559

Using ubuntu-bug correctly opens the GTK gui, but after hitting "Send" a new chromium instance is opened with apparently no page loaded.
No errors are displayed, only this warning (although before hitting send):
```
/usr/share/apport/apport-gtk:16: PyGIWarning: Wnck was imported without specifying a version first. Use gi.require_version('Wnck', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import GLib, Wnck, GdkX11, Gdk
```

Workaround: making Firefox the default browser from within Firefox itself.

Note that ubuntu-bug --save PATH works fine.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: apport 2.20.1-0ubuntu2
ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
Uname: Linux 4.4.0-18-generic x86_64
ApportLog:

ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CrashReports: 640:1000:116:18680539:2016-04-14 23:05:48.336127519 +0100:2016-04-14 23:05:49.336127519 +0100:/var/crash/_usr_bin_compiz.1000.crash
CurrentDesktop: Unity
Date: Fri Apr 15 12:14:40 2016
InstallationDate: Installed on 2016-04-14 (0 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160414)
PackageArchitecture: all
SourcePackage: apport
UpgradeStatus: No upgrade log present (probably fresh install)

[nicola dmt (nicola-dmt)]

I found that the issue may be with chromium itself, not apport: a different application that is expected to open a given URL (ipython notebook) fails to do that as well.

Using chromium-browser 49.0.2623.108-0ubuntu1.1233

(Note that chromium correctly open a requested URL if launched as "chromium-browser <url>" from the command line).