Merge branch 'fc/completion'

* fc/completion:
  completion: remove __git_index_file_list_filter()
  completion: add space after completed filename
  completion: add hack to enable file mode in bash < 4
  completion: refactor __git_complete_index_file()
  completion: refactor diff_index wrappers
  completion: use __gitcompadd for __gitcomp_file
  completion; remove unuseful comments
  completion: document tilde expansion failure in tests
  completion: add file completion tests

diff --cc contrib/completion/git-completion.bash
Simple merge