notify-updates: ignore chown error

If running as normal user, chown will fail. This isn't a problem,
because the file is probably already owned by the correct user. The
whole point about this chown is to give access to the file for normal
user, so if the write succeeded, it isn't needed.

qubes-rpc/qubes-notify-updates

@@ -61,7 +61,10 @@ def main():
         update_f = open(source_vm.dir_path + '/' + vm_files["updates_stat_file"], "w")
         update_f.write(update_count)
         update_f.close()
+        try:
             os.chown(source_vm.dir_path + '/' + vm_files["updates_stat_file"], -1, qubes_gid)
+        except OSError:
+            pass
     elif source_vm.template is not None:
         # Hint about updates availability in template
         # If template is running - it will notify about updates itself
@@ -79,7 +82,10 @@ def main():
             update_f = open(stat_file, "w")
             update_f.write(update_count)
             update_f.close()
+            try:
                 os.chown(stat_file, -1, qubes_gid)
+            except OSError:
+                pass
         else:
             print >> sys.stderr, 'Ignoring notification of no updates'