patch 8.2.4334: command line popup menu not positioned correctly

Problem:    Command line popup menu not positioned correctly.
Solution:   Also use vim_strsize() on the existing text. (Naruhiko Nishino,
            closes #9727)
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 175647d..c40d653 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -2141,6 +2141,17 @@
   call TermWait(buf)
   call VerifyScreenDump(buf, 'Test_wildmenu_pum_31', {})
 
+  " Tests a directory name contained full-width characters.
+  call mkdir('Xdir/あいう', 'p')
+  call writefile([], 'Xdir/あいう/abc')
+  call writefile([], 'Xdir/あいう/xyz')
+  call writefile([], 'Xdir/あいう/123')
+
+  call term_sendkeys(buf, "\<C-U>set wildmode&\<CR>")
+  call term_sendkeys(buf, ":\<C-U>e Xdir/あいう/\<Tab>")
+  call TermWait(buf)
+  call VerifyScreenDump(buf, 'Test_wildmenu_pum_32', {})
+
   call term_sendkeys(buf, "\<C-U>\<CR>")
   call StopVimInTerminal(buf)
   call delete('Xtest')