They are only used if autocmd is available.
let NERDCreateDefaultMappings = 0
" Map toggle comment.
map <Leader><Leader> <plug>NERDCommenterToggle
+
+
+" AUTO COMMANDS
+
+" Use a custom auto group to prevent problems when the vimrc files is sourced
+" twice.
+if has("autocmd")
+ augroup vimrc
+ autocmd!
+
+" Use diff filetype for mercurial patches in patch queue.
+ autocmd BufReadPost */.hg/patches/* set filetype=diff
+
+ augroup END
+endif