Test test_empty_post_date_gmt_shimmed_using_post_date is buggy

[PressLabs]

The test_empty_post_date_gmt_shimmed_using_post_date works only on certain periods of time. The test must implement the Daylight Saving Time criteria in order to work properly all the time.

1) WP_Test_REST_Posts_Controller::test_empty_post_date_gmt_shimmed_using_post_date
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'2016-02-23T18:00:00'
+'2016-02-23T17:00:00'

[ocean90]

Thanks for the report, @PressLabs. We're already tracking this issue in #40136.