Comment 3 for bug 1171606

I'd rather have a package called non-upstreamed-contracts and throw every contract there, then remove them as they're getting upstreamed. This will require clever package versioning to work cleanly, but we can afford that.

It will also require proper existence and executability watches in Contractor (bug 912413) as well as support for TryExec key (bug 1171835) and, in the long run, OnlyShowIn key. So I'd say Contractor is not really ready for this yet.