patch 8.2.4671: 'wildignorecase' is sometimes not used for glob()

Problem:    'wildignorecase' is sometimes not used for glob().
Solution:   Also use 'wildignorecase' when there are no wildcards.
            (closes #10066, closes #8350)
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index fddf4ae..a19dd52 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -2821,6 +2821,8 @@
   " Sort output of glob() otherwise we end up with different
   " ordering depending on whether file system is case-sensitive.
   call assert_equal(['XGLOB2', 'Xglob1'], sort(glob('Xglob[12]', 0, 1)))
+  " wildignorecase shall be applied even when the pattern contains no wildcards.
+  call assert_equal('XGLOB2', glob('xglob2'))
   set wildignorecase&
 
   call delete('Xglob1')