Okay, so how about we try to clean-out the golang-github-golang-protobuf-1-3-dev packages from sid by updating existing packages to build against golang-github-golang-protobuf-1-5-dev instead?
I've managed to get golang-google-grpc in sid to build against golang/protobuf@v1.5 [1]. Moreover, I've managed to get notary, gnostic and
docker.io (all in sid) rebuilt on v1.5. I've verified that in all cases, we end up with a dependency on golang-google-protobuf-dev. This is expected, as golang/protobuf@v1.5 exposes the APIv1, but essentially produces forwarding code that uses the code from APIv2 in the golang-google-protobuf. Maybe we should update the package description of the to golang-github-golang-protobuf-1-5 package capture this point (better), right now I find it a bit misleading.
I expect this to cause some packages to break, because protoc-gen-go-1-5 is implemented as a "thin wrapper" around protoc-gen-go from the golang-google-protobuf package. This change was introduced in golang/protbuf@v1.4.0 [2] and causes some subtle behavioral changes. For instance, in the GRPC package I noticed that the new code generator is sensitive to non-existing include paths. in v1.3, you got away with a warning, I had to update the patch to avoid a compilation failure. There may be additional subtleties. However, this fallout should be somewhat manageable -- I was able to get to
docker.io fairly quickly.