def assert_repo!
      begin
        # Check if the repo fails to load at all.
        repo
      rescue Exception
        raise Thor::Error.new("#{repo_path} does not appear to be a git repository")
      end
      unless repo.repo.writable?
        raise Thor::Error.new("Git repository at #{repo.repo.path} is read-only")
      end
    end
def assert_repo!
      begin
        # Check if the repo fails to load at all.
        repo
      rescue Exception
        raise Thor::Error.new("#{repo_path} does not appear to be a git repository")
      end
      unless repo.repo.writable?
        raise Thor::Error.new("Git repository at #{repo.repo.path} is read-only")
      end
    end
Check that we are in a git repo that we have write access to.

 @api private
 @return [void]