Don't clobber v_s map

Author: tpope

plugin/surround.vim

@@ -551,7 +551,9 @@ if !exists("g:surround_no_mappings") || ! g:surround_no_mappings
   nmap ySS <Plug>YSsurround
   xmap S   <Plug>VSurround
   xmap gS  <Plug>VgSurround
-  xnoremap <silent> s :<C-U>echoerr 'surround.vim: Visual mode s has been removed in favor of S'<CR>
+  if maparg('s', 'x') ==# ''
+    xnoremap <silent> s :<C-U>echoerr 'surround.vim: Visual mode s has been removed in favor of S'<CR>
+  endif
   if !hasmapto("<Plug>Isurround","i") && "" == mapcheck("<C-S>","i")
     imap    <C-S> <Plug>Isurround
   endif