patch 8.2.3279: Vim9: cannot use block in cmdline window

Problem:    Vim9: cannot use block in cmdline window.
Solution:   Add EX_CMDWIN to the CMD_block flags. (closes #8689)
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index e6554e9..a624113 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -1262,7 +1262,7 @@
   # List results in multiple lines
   new
   setline(1, 'some text here')
-  s/text/\=['aaa', 'bbb', 'ccc']/ 
+  s/text/\=['aaa', 'bbb', 'ccc']/
   assert_equal(['some aaa', 'bbb', 'ccc', ' here'], getline(1, '$'))
   bwipe!
 enddef
@@ -1338,5 +1338,18 @@
   CheckScriptFailure(lines, 'E1186:', 1)
 enddef
 
+def Test_cmdwin_block()
+  augroup justTesting
+    autocmd BufEnter * {
+      echomsg 'in block'
+    }
+  augroup END
+  feedkeys('q:', 'xt')
+  redraw
+  feedkeys("aclose\<CR>", 'xt')
+
+  au! justTesting
+enddef
+
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker