Merge branch 'for-junio' of git://source.winehq.org/~julliard/git/git

* 'for-junio' of git://source.winehq.org/~julliard/git/git:
  git.el: Allow to commit even if there are no marked files.
  git.el: Add possibility to mark files directly in git-update-status-files.
  git.el: Add an insert file command.
  git.el: Never clear the status buffer, only update the files.
  git.el: Fix git-amend-commit to support amending an initial commit.
  git.el: Properly handle merge commits in git-amend-commit.
  git.el: Simplify handling of merge heads in the commit log-edit buffer.
  git.el: Remove the env parameter in git-call-process and git-call-process-string.
  git.el: Improve error handling for commits.