wrap a couple of wincmd calls in s:exec

this is to prevent autocmds from being fired when the tree is closed

plugin/NERD_tree.vim

@@ -3121,9 +3121,9 @@ function! s:closeTree()
 
     if winnr("$") != 1
         if winnr() == s:getTreeWinNum()
-            wincmd p
+            call s:exec("wincmd p")
             let bufnr = bufnr("")
-            wincmd p
+            call s:exec("wincmd p")
         else
             let bufnr = bufnr("")
         endif