Wrong UTC time while converting from CST by to_utc_timestamp UDFs

Error on Daylight Saving 2017

select to_utc_timestamp("2017-03-11 19:00:00",'CST');
OK
2017-03-12 01:00:00 --> expected 6 hr difference
Time taken: 0.08 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-11 20:00:00",'CST');
OK
2017-03-12 03:00:00 --> wrong 7 hr difference
Time taken: 0.088 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-11 21:00:00",'CST');
OK
2017-03-12 04:00:00--> wrong 7 hr difference
Time taken: 2.884 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-11 22:00:00",'CST');
OK
2017-03-12 05:00:00--> wrong 7 hr difference
Time taken: 0.075 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-11 23:00:00",'CST');
OK
2017-03-12 06:00:00 --> wrong 7 hr difference
Time taken: 0.068 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-12 00:00:00",'CST');
OK
2017-03-12 07:00:00 --> wrong 7 hr difference
Time taken: 4.769 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-12 01:00:00",'CST');
OK
2017-03-12 08:00:00 --> wrong 7 hr difference
Time taken: 0.066 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-12 02:00:00",'CST');
OK
2017-03-12 08:00:00 --> wrong 7 hr difference
Time taken: 0.066 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-12 03:00:00",'CST');
OK
2017-03-12 08:00:00 --> expected 5 hr
Time taken: 0.061 seconds, Fetched: 1 row(s)
hive> select to_utc_timestamp("2017-03-12 04:00:00",'CST');
OK
2017-03-12 09:00:00--> expected 5 hr
Time taken: 0.065 seconds, Fetched: 1 row(s)