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 filetype plugin file
" Language:         Mailcap configuration file
" Maintainer:       Nikolai Weibull <now@bitwi.se>
" Latest Revision:  2008-07-09

if exists("b:did_ftplugin")
  finish
endif
let b:did_ftplugin = 1

let s:cpo_save = &cpo
set cpo&vim

let b:undo_ftplugin = "setl com< cms< fo<"

setlocal comments=:# commentstring=#\ %s formatoptions-=t formatoptions+=croql

let &cpo = s:cpo_save
unlet s:cpo_save