def index
      @index ||= begin
        idx = @wiki.repo.index
        if (tree = options[:tree])
          idx.read_tree(tree)
        elsif (parent = parents.first)
          idx.read_tree(parent.tree.id)
        end
        idx
      end
    end
def index
      @index ||= begin
        idx = @wiki.repo.index
        if (tree = options[:tree])
          idx.read_tree(tree)
        elsif (parent = parents.first)
          idx.read_tree(parent.tree.id)
        end
        idx
      end
    end
Initializes the Committer.

 wiki    - The Gollum::Wiki instance that is being updated.
 options - The commit Hash details:
           :message   - The String commit message.
           :name      - The String author full name.
           :email     - The String email address.
           :parent    - Optional Gollum::Git::Commit parent to this update.
           :tree      - Optional String SHA of the tree to create the
                        index from.
           :committer - Optional Gollum::Committer instance.  If provided,
                        assume that this operation is part of batch of
                        updates and the commit happens later.

 Returns the Committer instance.
 Public: References the Git index for this commit.

 Returns a Gollum::Git::Index.