Failure to rollback t.timestamps when within a change_table migration

When running the following migration:

    def change
      change_table(:table_name) { |t| t/timestamps }
    end

The following error was produced:

    wrong number of arguments (2 for 1) .... /connection_adapters/abstract/schema_statements.rb:851:in `remove_timestamps'

This is due to `arguments` containing an empty hash as its second
element.
Why not `==`? This should be an `elsif` as well.