patch 9.0.0191: messages test fails; window size incorrect

Problem:    Messages test fails; window size incorrect when 'cmdheight' is
            made smaller.
Solution:   Properly cleanup after test with cmdheight zero.  Resize windows
            correctly when 'cmdheight' gets smaller.
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 92adbd1..521312a 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -239,6 +239,11 @@
   call term_sendkeys(buf, ":set cmdheight-=2\<CR>")
   call VerifyScreenDump(buf, 'Test_changing_cmdheight_4', {})
 
+  " reducing window size and then setting cmdheight 
+  call term_sendkeys(buf, ":resize -1\<CR>")
+  call term_sendkeys(buf, ":set cmdheight=1\<CR>")
+  call VerifyScreenDump(buf, 'Test_changing_cmdheight_5', {})
+
   " clean up
   call StopVimInTerminal(buf)
   call delete('XTest_cmdheight')