I tried generating .proto files using make proto

It generated files with a lot of differences as discussed in #1682 and the helpful top comment also got removed. (gist attached)

As alertmanager uses the gogo/protobuf implementation,

from the gogo/protobuf readme

protoc-gen-gogofast (same as gofast, but imports gogoprotobuf)
protoc-gen-gogofaster (same as gogofast, without XXX_unrecognized, less pointer fields)
protoc-gen-gogoslick (same as gogofaster, but with generated string, gostring and equal methods)

and genproto.sh uses gogofast

so it is supposed to generate the XXX_unrecognized when using gogofast but the files in master do not show any XXX_unrecognized

What did you do?

- Install protoc`v3.5.1`
- go install github.com/gogo/protobuf/protoc-gen-gogo
- go install github.com/gogo/protobuf/protoc-gen-gogofast
- go get github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway
- go get golang.org/x/tools/cmd/goimports

I even tried installing downto v0.4 of gogo/protobuf for protoc-gen-gogo

What did you expect to see?
What @juliusv generated,
diff: https://gist.github.com/juliusv/033a489a93c118be9184457c44b9cc63

What did you see instead? Under which circumstances?
make proto
diff: https://gist.github.com/geekodour/52ae6d8283996b88c064526f97aafdcf

Environment

• System information:
  Linux 4.13.9-300.fc27.x86_64 x86_64
• Alertmanager version:
  master

cc: @fabxc @juliusv