Actually run chkstat on the SUSE image

A trailing comma made args.cmd a tuple holding the argv list, so
fancy_chroot called startswith on a list and the child died before exec.
permissions.local was written but never applied, leaving ssh-keysign
0755 and hostbased auth inoperative on SUSE diskless images.

imgutil/imgutil

@@ -667,7 +667,7 @@ class SuseHandler(OsHandler):
         args.cmd = ['groupadd', 'ssh_keys']
         run_constrainedx(fancy_chroot, (args,
                                         self.targpath))
-        args.cmd = ['chkstat', '--system', '--set'],
+        args.cmd = ['chkstat', '--system', '--set']
         run_constrainedx(fancy_chroot, (args,
                                         self.targpath))