gnome-software crashed with SIGSEGV in g_string_truncate()

[Jean-Baptiste Lallement]

Test Case:
1. Download opera deb file from opera.com
2. Run the file to launch gnome-software
3. Install it
4. Proceed with the debconf prompt

Actual result
It hangs.

ProblemType: Crash
DistroRelease: Ubuntu 18.04
Package: gnome-software 3.26.3-2ubuntu1
ProcVersionSignature: Ubuntu 4.13.0-25.29-generic 4.13.13
Uname: Linux 4.13.0-25-generic x86_64
ApportVersion: 2.20.8-0ubuntu6
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Jan 30 10:51:48 2018
ExecutablePath: /usr/bin/gnome-software
InstallationDate: Installed on 2013-09-03 (1609 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Alpha amd64 (20130902)
InstalledPlugins:
 gnome-software-plugin-flatpak 3.26.3-2ubuntu1
 gnome-software-plugin-limba N/A
 gnome-software-plugin-snap 3.26.3-2ubuntu1
ProcCmdline: /usr/bin/gnome-software --gapplication-service
ProcEnviron:
 XDG_RUNTIME_DIR=<set>
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=fr_FR.UTF-8
SegvAnalysis:
 Segfault happened at: 0x7fcf4d7ed9e8 <g_string_truncate+24>: movb $0x0,(%rdx,%rsi,1)
 PC (0x7fcf4d7ed9e8) ok
 source "$0x0" ok
 destination "(%rdx,%rsi,1)" (0x7fcf4ca22480) in non-writable VMA region: 0x7fcf4c8d1000-0x7fcf4cfcc000 r-xp /usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.26
SegvReason: writing VMA /usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.26
Signal: 11
SourcePackage: gnome-software
StacktraceTop:
 g_string_truncate (string=0x55da39040220, len=len@entry=0) at ../../../../glib/gstring.c:371
 g_io_channel_shutdown (channel=0x55da37da4710, flush=0, err=0x7ffff08364b8) at ../../../../glib/giochannel.c:511
 () at /usr/lib/x86_64-linux-gnu/libpackagekit-glib2.so.18
 g_main_dispatch (context=0x55da36e2a1c0) at ../../../../glib/gmain.c:3148
 g_main_context_dispatch (context=context@entry=0x55da36e2a1c0) at ../../../../glib/gmain.c:3813
Title: gnome-software crashed with SIGSEGV in g_string_truncate()
UpgradeStatus: Upgraded to bionic on 2018-01-26 (3 days ago)
UserGroups: adm autopilot cdrom dip docker libvirt libvirtd lpadmin lxd plugdev sambashare stapdev stapsys stapusr sudo

[Apport retracing service (apport)]

StacktraceTop:
 g_string_truncate (string=0x55da39040220, len=len@entry=0) at ../../../../glib/gstring.c:371
 g_io_channel_shutdown (channel=0x55da37da4710, flush=flush@entry=0, err=err@entry=0x7ffff08364b8) at ../../../../glib/giochannel.c:511
 pk_client_helper_copy_stdout_cb (source=<optimized out>, condition=<optimized out>, client_helper=<optimized out>) at pk-client-helper.c:173
 g_main_dispatch (context=0x55da36e2a1c0) at ../../../../glib/gmain.c:3148
 g_main_context_dispatch (context=context@entry=0x55da36e2a1c0) at ../../../../glib/gmain.c:3813