This patch ensures '.desktop' files are picked up in the system profile
and not in the directories listed in $XDG_DATA_DIRS.  The latter includes
'gnome-session.desktop', which should be used if it's in
/run/current-system/profile, and only then.

Fixes <https://bugs.gnu.org/37831>.

diff -ur a/daemon/gdm-session.c b/daemon/gdm-session.c
--- a/daemon/gdm-session.c	2019-09-25 10:40:24.000000000 -0400
+++ b/daemon/gdm-session.c	2020-04-18 18:30:02.671856808 -0400
@@ -348,24 +348,18 @@
         GArray *search_array = NULL;
         char **search_dirs;
         int i;
-        const gchar * const *system_data_dirs = g_get_system_data_dirs ();
 
         static const char *x_search_dirs[] = {
                 "/etc/X11/sessions/",
                 DMCONFDIR "/Sessions/",
                 DATADIR "/gdm/BuiltInSessions/",
-                DATADIR "/xsessions/",
+                "/run/current-system/profile/share/xsessions/"
         };
 
         static const char *wayland_search_dir = DATADIR "/wayland-sessions/";
 
         search_array = g_array_new (TRUE, TRUE, sizeof (char *));
 
-        for (i = 0; system_data_dirs[i]; i++) {
-                gchar *dir = g_build_filename (system_data_dirs[i], "xsessions", NULL);
-                g_array_append_val (search_array, dir);
-        }
-
         g_array_append_vals (search_array, x_search_dirs, G_N_ELEMENTS (x_search_dirs));
 
 #ifdef ENABLE_WAYLAND_SUPPORT
@@ -373,16 +367,7 @@
 #ifdef ENABLE_USER_DISPLAY_SERVER
                 g_array_prepend_val (search_array, wayland_search_dir);
 
-                for (i = 0; system_data_dirs[i]; i++) {
-                        gchar *dir = g_build_filename (system_data_dirs[i], "wayland-sessions", NULL);
-                        g_array_insert_val (search_array, i, dir);
-                }
 #else
-                for (i = 0; system_data_dirs[i]; i++) {
-                        gchar *dir = g_build_filename (system_data_dirs[i], "wayland-sessions", NULL);
-                        g_array_append_val (search_array, dir);
-                }
-
                 g_array_append_val (search_array, wayland_search_dir);
 #endif
         }
diff -ur a/libgdm/gdm-sessions.c b/libgdm/gdm-sessions.c
--- a/libgdm/gdm-sessions.c	2019-10-07 04:53:35.000000000 -0400
+++ b/libgdm/gdm-sessions.c	2020-04-18 18:31:42.491348691 -0400
@@ -245,19 +245,12 @@
                 "/etc/X11/sessions/",
                 DMCONFDIR "/Sessions/",
                 DATADIR "/gdm/BuiltInSessions/",
-                DATADIR "/xsessions/",
+                "/run/current-system/profile/share/xsessions/"
         };
 
         names_seen_before = g_hash_table_new (g_str_hash, g_str_equal);
         xorg_search_array = g_ptr_array_new_with_free_func (g_free);
 
-        const gchar * const *system_data_dirs = g_get_system_data_dirs ();
-
-        for (i = 0; system_data_dirs[i]; i++) {
-                session_dir = g_build_filename (system_data_dirs[i], "xsessions", NULL);
-                g_ptr_array_add (xorg_search_array, session_dir);
-        }
-
         for (i = 0; i < G_N_ELEMENTS (xorg_search_dirs); i++) {
                 g_ptr_array_add (xorg_search_array, g_strdup (xorg_search_dirs[i]));
         }
@@ -269,11 +262,6 @@
 
         wayland_search_array = g_ptr_array_new_with_free_func (g_free);
 
-        for (i = 0; system_data_dirs[i]; i++) {
-                session_dir = g_build_filename (system_data_dirs[i], "wayland-sessions", NULL);
-                g_ptr_array_add (wayland_search_array, session_dir);
-        }
-
         for (i = 0; i < G_N_ELEMENTS (wayland_search_dirs); i++) {
                 g_ptr_array_add (wayland_search_array, g_strdup (wayland_search_dirs[i]));
         }
d><td><a href='/guix/commit/tests/services/telephony.scm?id=10f554700c417b84c22c56fdd007567a52c45d75'>Reinstate "services: Add a service for Jami."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 4673f817938d9d2b1b40a072ab2e0c44a32ccc97, which reverted
commit 69dcc24c9f0cdfea674eb690e7755d26a25ced2b with the fix detailed below.

Thanks to Christopher Baines for reporting the failure and proposing a fix.

* guix/self.scm (compiled-guix) [*system-test-modules*]: Add the test data
files via the 'extra-files' argument.
* gnu/local.mk (dist_patch_DATA): Move the tests/data/jami-dummy-account.dat
file to...
* gnu/local.mk (MODULES_NOT_COMPILED): ... here.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2021-08-02 15:48:59 -0400'>2021-08-02</span></td><td><a href='/guix/commit/tests/services/telephony.scm?id=4673f817938d9d2b1b40a072ab2e0c44a32ccc97'>Revert "services: Add a service for Jami."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 69dcc24c9f0cdfea674eb690e7755d26a25ced2b.  It broke 'guix
pull'.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2021-08-02 15:15:02 -0400'>2021-08-02</span></td><td><a href='/guix/commit/tests/services/telephony.scm?id=69dcc24c9f0cdfea674eb690e7755d26a25ced2b'>services: Add a service for Jami.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/telephony.scm (string-or-computed-file?)
(string-list?, account-fingerprint-list?): New procedures.
(maybe-string-list, maybe-account-fingerprint-list)
(maybe-boolean, maybe-string, jami-account-list): New configuration field
types.
(serialize-string-list, serialize-boolean, serialize-string)
(jami-account, jami-account-&gt;alist, jami-configuration)
(jami-account-list?, jami-account-list-maybe): New procedures.
(%jami-accounts): New variable.
(jami-configuration-&gt;command-line-arguments): New procedure.
(jami-dbus-session-activation, jami-shepherd-services): New procedures.
(jami-service-type): New variable.
* gnu/build/jami-service.scm: New file.
* gnu/tests/data/jami-dummy-account.dat: Likewise.
* gnu/tests/telephony.scm: Likewise.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register them.
* Makefile.am (SCM_TESTS): Register the test file.
(dist_patch_DATA): Register the new data file.
* doc/guix.texi (Telephony Services): Document it.
</span></span></td><td>Maxim Cournoyer</td></tr>