commit https://github.com/vim/vim/commit/5c71994f4ee5f87d4cce990dbc9684c70b1e108b Author: Bram Moolenaar <Bram@vim.org> Date: Sat Jul 9 23:40:45 2016 +0200 patch 7.4.2015 Problem: When a file gets a name when writing it 'acd' is not effective. (Dan Church) Solution: Invoke DO_AUTOCHDIR after writing the file. (Allen Haim, closes #777, closes #803) Add test_autochdir() to enable 'acd' before "starting" is reset.

" Test 'autochdir' behavior

if !exists("+autochdir")
  finish
endif

func Test_set_filename()
  call test_autochdir()
  set acd
  new
  w samples/Xtest
  call assert_equal("Xtest", expand('%'))
  call assert_equal("samples", substitute(getcwd(), '.*/\(\k*\)', '\1', ''))
  bwipe!
  set noacd
  call delete('samples/Xtest')
endfunc