I tried to change the date on the AM335x evm board today. I am using SDK 7.0,. kernel 3.12. This was the results:
root@am335x-evm:~# date +%Y%m%d -s "20150207"
20190815
root@am335x-evm:~# date
Thu Aug 15 02:07:06 UTC 2019
root@am335x-evm:~#
Is there a known issue with the date command?