Sale price scheduled dates get changed during migration

[leewillis77]

The migration of sale price scheduled dates goes awry and it looks like it's out because it's taking timezones into account whereas the store data is UTC (I think).

Data before migration:

mysql > SELECT * from wc_postmeta WHERE meta_id IN (255,256);
+---------+---------+------------------------+--------------+
| meta_id | post_id | meta_key               | meta_value   |
+---------+---------+------------------------+--------------+
|     255 |      23 | _sale_price_dates_from | 1538348400   |
|     256 |      23 | _sale_price_dates_to   | 1561849200   |

Which is displayed in the UI as:

Data after migration:

mysql> select date_on_sale_from, date_on_sale_to from wc_wc_products where product_id = 23 \G ;
*************************** 1. row ***************************
date_on_sale_from: 2018-09-30 23:00:00
  date_on_sale_to: 2019-06-29 23:00:00
1 row in set (0.00 sec)

Which is displayed in the UI as:

WordPress' timezone is set to "London" (Currently UTC+1)