patch 8.2.0396: cmdexpand.c insufficiently tested

Problem:    Cmdexpand.c insufficiently tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5789)
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 7f057e2..e99ab7f 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -2495,7 +2495,7 @@
 
   call term_sendkeys(g:buf0, "exit\<CR>")
   sleep 100m
-  exe g:buf0 .. 'bwipe'
+  exe g:buf0 .. 'bwipe!'
   set hidden&
 endfunc