patch 8.2.1121: command completion not working after ++arg

Problem:    Command completion not working after ++arg.
Solution:   Move skipping up. (Christian Brabandt, closes #6382)
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 2a3112a..eb213f1 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -1593,8 +1593,11 @@
     call feedkeys(":r! ++enc=utf-8 r\<c-a>\<c-b>\"\<cr>", 'tx')
     call assert_notmatch('^"r!.*\<runtest.vim\>', @:)
     call assert_match('^"r!.*\<rm\>', @:)
+
+    call feedkeys(":r ++enc=utf-8 !rm\<c-a>\<c-b>\"\<cr>", 'tx')
+    call assert_notmatch('^"r.*\<runtest.vim\>', @:)
+    call assert_match('^"r ++enc\S\+ !.*\<rm\>', @:)
   endif
 endfunc
 
-
 " vim: shiftwidth=2 sts=2 expandtab