vim-patch:8.2.0921: CTRL-W T in cmdline window causes trouble

Problem:    CTRL-W T in cmdline window causes trouble.
Solution:   Disallow CTRL-W T in the cmdline window.  Add more tests.
            (Naruhiko Nishino, closes vim/vim#6219)
4fdb8bd054

Test already passes in Nvim because of later patches.
Move Test_cmdwin_jump_to_win() to the right place.

src/nvim/window.c

@@ -331,6 +331,7 @@ newwindow:
 
   // move window to new tab page
   case 'T':
+    CHECK_CMDWIN;
     if (one_window(curwin)) {
       msg(_(m_onlyone));
     } else {