pushing fixes to stable before closing bugs

I noticed a general tendency to close bugs affecting stable before
pushing the fix to stable.

One recent example is <https://bugs.gentoo.org/show_bug.cgi?id=399291>,
but there are more.

The idea is that if you only fix in ~arch, you risk a serious and
_known_ regression in stable, which could be easily avoided.

Do you have any ideas how do we:

1. Make as many developers (everyone?) as possible aware of this.

2. Handle already closed bugs with no fix in stable? I've seen people
closing the bugs again.

Paweł