Search highlight is not cleared when there is no match

Recently I experienced an issue multiple times. When I search something and there is no match in the current buffer, then search highlight is not cleared even if I move the cursor.

This is the minimal vimrc to reproduce:
``` vim
set nocompatible
filetype off

call plug#begin()
Plug 'junegunn/vim-slash'
call plug#end()
```

Open Vim and search anything, for example, `/test`. Then we'll see `E486: Pattern not found: test` error. Just insert that text, `test` to the buffer. Then it'll be immediately highlighted. If I turn off the search highlight, I need to type `:noh` or search that term again and move the cursor.

This issue is clearer when there are multiple windows open. One having no match, and the other having one match or more. If the current buffer doesn't have a match, then the search highlight of the other is not cleared when I move the cursor.