def get_requirement_revision(cls, location):
        """
        Return the changeset identification hash, as a 40-character
        hexadecimal string
        """
        current_rev_hash = cls.run_command(
            ['parents', '--template={node}'],
            show_stdout=False, cwd=location).strip()
        return current_rev_hash

        Return the changeset identification hash, as a 40-character
        hexadecimal string
        
product/gradle-plugin/src/main/python/pip/_internal/vcs/mercurial.py