bug#39711: Epiphany fails to launch Evince

[Ludovic Courtès]

Hello,

When running Epiphany on a non-GNOME system with:

  guix environment --ad-hoc epiphany -- epiphany

and opening a PDF, it fails to launch Evince (referred to as
“Dokumentmontrilo” below :-)) and crashes:

--8<---------------cut here---------------start------------->8---
$ guix environment --ad-hoc epiphany -- epiphany

** (epiphany:2419): WARNING **: 09:33:46.938: 
webkit_web_context_set_web_process_count_limit is deprecated and does nothing. 
Limiting the number of web processes is no longer possible for security reasons
** Message: 09:33:47.162: Remote error from secret service: 
org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.secrets was 
not provided by any .service files

** (epiphany:2419): WARNING **: 09:33:47.162: Failed to search secrets in 
password schema: The name org.freedesktop.secrets was not provided by any 
.service files

** (epiphany:2419): WARNING **: 09:45:47.949: Failed to acquire session 
inhibitor for active download. Is gnome-session running?

** (epiphany:2419): WARNING **: 09:45:51.859: Failed to launch 
Dokumentmontrilo: No s'ha pogut executar el procés fill «gio-launch-desktop» 
(Dosiero aŭ dosierujo ne ekzistas)

(epiphany:2419): GLib-GIO-CRITICAL **: 09:45:51.860: g_app_info_launch_uris: 
assertion 'G_IS_APP_INFO (appinfo)' failed
--8<---------------cut here---------------end--------------->8---

The problem is that ‘gio-launch-desktop’ is not found in $PATH.

Ludo’.