Empty error and access log

[rick_pri]

We recently noticed this on our servers and we were using USR1 for
postrotation which wasn't working as expected.  We changed the post rotation
command to be HUP and this fixed the issues of rotation being borked.

http://nginx.org/en/docs/control.html
It says that USR1 should reopen logfiles after they have been renamed but we
found that this didn't work

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,285708,285717#msg-285717