Correct local variable namespace

NERDTree keeps 'No Name' buffer after deleting current node 'md' preservim#755 (closes preservim#755) preservim#756

nerdtree_plugin/fs_menu.vim

@@ -58,15 +58,15 @@ function! s:promptToDelBuffer(bufnum, msg)
         " Go to the next buffer in buffer list if at least one extra buffer is listed
         " Otherwise open a new empty buffer
         if v:version >= 800
-            let s:listedBufferCount = len(getbufinfo({'buflisted':1}))
+            let l:listedBufferCount = len(getbufinfo({'buflisted':1}))
         elseif v:version >= 702
-            let s:listedBufferCount = len(filter(range(1, bufnr('$')), 'buflisted(v:val)'))
+            let l:listedBufferCount = len(filter(range(1, bufnr('$')), 'buflisted(v:val)'))
         else
             " Ignore buffer count in this case to make sure we keep the old
             " behavior
-            let s:listedBufferCount = 0
+            let l:listedBufferCount = 0
         endif
-        if s:listedBufferCount > 1
+        if l:listedBufferCount > 1
             exec "tabdo windo if winbufnr(0) == " . a:bufnum . " | exec ':bnext! ' | endif"
         else
             exec "tabdo windo if winbufnr(0) == " . a:bufnum . " | exec ':enew! ' | endif"