patch 8.2.2447: 'foldlevel' not applied to folds restored from session

Problem:    'foldlevel' not applied to folds restored from session.
Solution:   Set 'foldlevel' after creaiting the folds. (closes #7767)
diff --git a/src/testdir/test_mksession.vim b/src/testdir/test_mksession.vim
index 723eb8e..82c96ce 100644
--- a/src/testdir/test_mksession.vim
+++ b/src/testdir/test_mksession.vim
@@ -504,6 +504,32 @@
   call delete('Xtestview')
 endfunc
 
+func Test_mkview_open_folds()
+  enew!
+
+  call append(0, ['a', 'b', 'c'])
+  1,3fold
+  " zR affects 'foldlevel', make sure the option is applied after the folds
+  " have been recreated.
+  normal zR
+  write! Xtestfile
+
+  call assert_equal(-1, foldclosed(1))
+  call assert_equal(-1, foldclosed(2))
+  call assert_equal(-1, foldclosed(3))
+
+  mkview! Xtestview
+  source Xtestview
+
+  call assert_equal(-1, foldclosed(1))
+  call assert_equal(-1, foldclosed(2))
+  call assert_equal(-1, foldclosed(3))
+
+  call delete('Xtestview')
+  call delete('Xtestfile')
+  %bwipe
+endfunc
+
 " Test :mkview with a file argument.
 func Test_mkview_file()
   " Create a view with line number and a fold.