Testing for backports of security/stable updates

[Evan Broder]

As part of trying to do a slightly better job of handling security and
stable updates, I'd like to propose reducing our testing requirements
for those backports.

Proposal: For stable and security updates of backported packages which
are not new upstream versions, it is not necessary to test reverse
dependencies. The only testing required is builds/installs/runs of the
package itself.

Objections to making this official backports policy?

- Evan