patch 8.2.0629: setting a boolean option to v:false does not work

Problem:    Setting a boolean option to v:false does not work.
Solution:   Do not use the string representation of the value. (Christian
            Brabandt, closes #5974)
diff --git a/src/testdir/test_options.vim b/src/testdir/test_options.vim
index e03d7e9..dec8288 100644
--- a/src/testdir/test_options.vim
+++ b/src/testdir/test_options.vim
@@ -899,4 +899,18 @@
   set shiftwidth&
 endfunc
 
+" Test for setting option values using v:false and v:true
+func Test_opt_boolean()
+  set number&
+  set number
+  call assert_equal(1, &nu)
+  set nonu
+  call assert_equal(0, &nu)
+  let &nu = v:true
+  call assert_equal(1, &nu)
+  let &nu = v:false
+  call assert_equal(0, &nu)
+  set number&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab