HUE-8737 [notebook] Fix notebook unit test in py3
HUE-8737 [notebook] Fix notebook unit test in py3

kawamon/hue,kawamon/hue,kawamon/hue,cloudera/hue,kawamon/hue,kawamon/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,kawamon/hue,kawamon/hue,kawamon/hue,cloudera/hue,cloudera/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,cloudera/hue,cloudera/hue,cloudera/hue,kawamon/hue,kawamon/hue,cloudera/hue,kawamon/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue