Same as add_cmd_output, except that it wraps command in
        "scl enable" call and sets proper PATH.

def add_cmd_output_scl(self, scl, cmds, **kwargs):
        """Same as add_cmd_output, except that it wraps command in
        "scl enable" call and sets proper PATH.
        """
        if isinstance(cmds, six.string_types):
            cmds = [cmds]
        scl_cmds = []
        for cmd in cmds:
            scl_cmds.append(self.convert_cmd_scl(scl, cmd))
        self.add_cmd_output(scl_cmds, **kwargs)