>>> json.dumps({'kernel_versions': [('test1', '', '1.2'), ('test2', '', '1.2'), ('test2', 'reboot_to_backport', '1.3~utopic')]})
'{"kernel_versions": [["test1", "", "1.2"], ["test2", "", "1.2"], ["test2", "reboot_to_backport", "1.3~utopic"]]}'