Fix Transition to SIGUSR2 in oslo.reports breaks upgrade
Fix Transition to SIGUSR2 in oslo.reports breaks upgrade

In I9d3b6079ba2cca41fe4723723a6f80b2c3c0b9c0, we broke backward
compatability when we switched from SIGUSR1 to SIGUSR2. This breaks
grenade jobs (Example https://review.openstack.org/#/c/238479/).

So for now, let's register both SIGUSR1 and SIGUSR2 and trigger a
warning in the log that SIGUSR1 has been deprecated. We should
remove use of SIGUSR1 in the O release. Hopefully this does not
break anything as when running under mod_wsgi SIGUSR1 is just
ignored (and SIGUSR2 will work) and both signals will work
under eventlet.

Closes-Bug: #1510740
Change-Id: I54ba70557f441fbd10eb085f79d594a9a33e1f11

openstack/oslo.reports