launchpad... how to add a backport dependency to a PPA.

[Peter Silva]

Hi folks,

I have a package:  https://launchpad.net/metpx-sarrac
that I have a recipe that auto builds it for 18.04, but it depends on a version
of a package where the distro version is too old in older releases.

https://launchpad.net/~ssc-hpc-chp-spc/+archive/ubuntu/metpx-daily

So I would like for the PPA to build & contain a back-ported version
of the dependency.

librabbitmq > 0.8.0

Do I create a project librabbitmq0_8 ? and build it as a package?
I know 0.8.0 builds fine on 16.04, and it will not force any other dependencies.
I don''t want to pull all sorts of other dependencies (I want the PPA
to use default repositories in general.)  Just need to override this
one.

What would be recommendend ways to do that?