HOWTO review backport PRs

Each backport PR (or backport tracker issue) should state:

1. what bug is fixed
2. why this fix is the minimal way to do it
3. why does this need to be fixed in <release>

For backport PRs opened by others, the role of the Stable Releases and Backports team members is to make sure these three questions are answered.

For backport PRs opened by members of the Stable Releases and Backports team, the team member should consider these questions and answer them in the PR or tracker issue. If the backporter does not feel comfortable answering the questions, it's better to ask someone else to do the backport. For example, one can post on the #ceph-devel IRC channel and ask who would be a suitable person to ask for help with the backport.

Answering these three questions in advance is important because it saves time of the leads who are involved in the code review process. Typically there will be two stable releases that we are backporting to. The "bar" for getting a backport into the older (more mature) stable release is higher.