commit https://github.com/vim/vim/commit/9f5842e63fc63d438cbffcec503e072a06f74dc2 Author: Bram Moolenaar <Bram@vim.org> Date: Sun May 29 16:17:08 2016 +0200 patch 7.4.1857 Problem: When a channel appends to a buffer that is 'nomodifiable' there is an error but appending is done anyway. Solution: Add the 'modifiable' option. Refuse to write to a 'nomodifiable' when the value is 1.

" Vim indent file
" Language:      BibTeX
" Maintainer:    Dorai Sitaram <ds26@gte.com>
" URL:		 http://www.ccs.neu.edu/~dorai/vimplugins/vimplugins.html
" Last Change:   2005 Mar 28

" Only do this when not done yet for this buffer
if exists("b:did_indent")
  finish
endif
let b:did_indent = 1

setlocal cindent

let b:undo_indent = "setl cin<"