patch 8.2.4282: restricted mode requires the -Z command line option

Problem:    Restricted mode requires the -Z command line option.
Solution:   Use restricted mode when $SHELL ends in "nologin" or "false".
            (closes #9681)
diff --git a/src/testdir/test_restricted.vim b/src/testdir/test_restricted.vim
index 22ca2f8..f743fbf 100644
--- a/src/testdir/test_restricted.vim
+++ b/src/testdir/test_restricted.vim
@@ -105,6 +105,14 @@
   if RunVim([], [], '-Z --clean -S Xrestricted')
     call assert_equal([], readfile('Xresult'))
   endif
+  call delete('Xresult')
+  if has('unix') && RunVimPiped([], [], '--clean -S Xrestricted', 'SHELL=/bin/false ')
+    call assert_equal([], readfile('Xresult'))
+  endif
+  call delete('Xresult')
+  if has('unix') && RunVimPiped([], [], '--clean -S Xrestricted', 'SHELL=/sbin/nologin')
+    call assert_equal([], readfile('Xresult'))
+  endif
 
   call delete('Xrestricted')
   call delete('Xresult')