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]));
         }
/tr>
<tr><td><span title='2018-10-14 23:48:49 +0200'>2018-10-14</span></td><td><a href='/guix/commit/etc/guix-install.sh?id=2510bd87562bfee9d82348f1c08dd78ccea12dd1'>guix-install.sh: Recognize armhf-linux.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-05-19 22:47:07 +0200'>2018-05-19</span></td><td><a href='/guix/commit/etc/guix-install.sh?id=593fe736674fadedd961c499e5758fa9c96a57aa'>guix-install.sh: Fix chk_require exiting without warning.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2018-03-29 07:03:37 +0200'>2018-03-29</span></td><td><a href='/guix/commit/etc/guix-install.sh?id=3cd4447f5639f45b7d833f6fb2adce11ea15ba1d'>guix-install.sh: Explicitly set root's home directory.</a><span class='msg-avail'>...</span></td><td>Chris Marusich</td></tr>
<tr><td><span title='2018-02-21 22:14:39 +0200'>2018-02-21</span></td><td><a href='/guix/commit/etc/guix-install.sh?id=ea6b1baec7515ec941f35c186ab314ec1c844250'>etc: guix-install.sh: Add aarch64-linux support.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2018-01-30 03:48:04 +0100'>2018-01-30</span></td><td><a href='/guix/commit/etc/guix-install.sh?id=6f4e8693e7b0c5d830eafa8a69c3559390f13369'>etc: Add installation script.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>