Bug in to_timestamp().

Hi,

It's look like bug in to_timestamp() function when format string has more whitespaces compare to input string, see below:

Ex.1: Two white spaces before HH24 whereas one before input time string

postgres=# SELECT TO_TIMESTAMP('2016-06-13 15:43:36', 'YYYY/MM/DD HH24:MI:SS');
to_timestamp
------------------------
2016-06-13 05:43:36-07 <— incorrect time
(1 row)

Ex.2: One whitespace before YYYY format string

postgres=# SELECT TO_TIMESTAMP('2016/06/13 15:43:36', ' YYYY/MM/DD HH24:MI:SS');
to_timestamp
------------------------------
0016-06-13 15:43:36-07:52:58 <— incorrect year
(1 row)

If there are one or more consecutive whitespace in the format, we should skip those as long as we could get an actual field.
Thoughts?
Thanks & Regards,
Amul Sul