Try to open the dconf cache directly instead of always trying to create the
directory path first (unveil).

Index: shm/dconf-shm.c
--- shm/dconf-shm.c.orig
+++ shm/dconf-shm.c
@@ -53,23 +53,29 @@ dconf_shm_open (const gchar *name)
   gchar *filename;
   void *memory;
   gint fd;
+  gint flags = O_RDWR | O_CREAT;
+  gint mode = 0600;
 
   shmdir = dconf_shm_get_shmdir ();
   filename = g_build_filename (shmdir, name, NULL);
   memory = NULL;
   fd = -1;
 
-  if (g_mkdir_with_parents (shmdir, 0700) != 0)
-    {
-      g_critical ("unable to create directory '%s': %s.  dconf will not work properly.", shmdir, g_strerror (errno));
-      goto out;
-    }
-
-  fd = open (filename, O_RDWR | O_CREAT, 0600);
+  fd = open (filename, flags, mode);
   if (fd == -1)
     {
-      g_critical ("unable to create file '%s': %s.  dconf will not work properly.", filename, g_strerror (errno));
-      goto out;
+      if (g_mkdir_with_parents (shmdir, 0700) != 0)
+        {
+          g_critical ("unable to create directory '%s': %s.  dconf will not work properly.", shmdir, g_strerror (errno));
+          goto out;
+        }
+
+      fd = open (filename, flags, mode);
+      if (fd == -1)
+        {
+          g_critical ("unable to create file '%s': %s.  dconf will not work properly.", filename, g_strerror (errno));
+          goto out;
+        }
     }
 
   /* ftruncate(fd, 1) is not sufficient because it does not actually