cannot find package "google/api"

[tmc]

Upstream protobuf package changed and the generated code now fails:

⚛ ~/go/src/github.com/gengo/grpc-gateway(master)$ git pull
Current branch master is up to date.
⚛ ~/go/src/github.com/gengo/grpc-gateway(master)$ git clean -xdf .
⚛ ~/go/src/github.com/gengo/grpc-gateway(master)$ make examples
go get github.com/golang/protobuf/protoc-gen-go
go build -o bin/protoc-gen-go github.com/golang/protobuf/protoc-gen-go
protoc -I /usr/local/bin//../include -I. -Ithird_party/googleapis --plugin=bin/protoc-gen-go --go_out=Mgoogle/protobuf/descriptor.proto=github.com/golang/protobuf/protoc-gen-go/descriptor,Mexamples/sub/message.proto=github.com/gengo/grpc-gateway/examples/sub,plugins=grpc:. examples/examplepb/echo_service.proto examples/examplepb/a_bit_of_everything.proto examples/examplepb/flow_combination.proto
protoc -I /usr/local/bin//../include  -Ithird_party/googleapis --plugin=bin/protoc-gen-go --go_out=Mgoogle/protobuf/descriptor.proto=github.com/golang/protobuf/protoc-gen-go/descriptor,Mexamples/sub/message.proto=github.com/gengo/grpc-gateway/examples/sub:third_party/googleapis third_party/googleapis/google/api/annotations.proto third_party/googleapis/google/api/http.proto
go build -o bin/protoc-gen-grpc-gateway github.com/gengo/grpc-gateway/protoc-gen-grpc-gateway
protoc -I /usr/local/bin//../include -I. -Ithird_party/googleapis --plugin=bin/protoc-gen-grpc-gateway --grpc-gateway_out=logtostderr=true,Mgoogle/protobuf/descriptor.proto=github.com/golang/protobuf/protoc-gen-go/descriptor,Mexamples/sub/message.proto=github.com/gengo/grpc-gateway/examples/sub:. examples/examplepb/echo_service.proto examples/examplepb/a_bit_of_everything.proto examples/examplepb/flow_combination.proto
protoc -I /usr/local/bin//../include -I. --plugin=bin/protoc-gen-go --go_out=Mgoogle/protobuf/descriptor.proto=github.com/golang/protobuf/protoc-gen-go/descriptor,Mexamples/sub/message.proto=github.com/gengo/grpc-gateway/examples/sub,plugins=grpc:. examples/sub/message.proto
⚛ ~/go/src/github.com/gengo/grpc-gateway(master)$ go build ./...
examples/examplepb/a_bit_of_everything.pb.go:10:8: cannot find package "google/api" in any of:
    /usr/local/Cellar/go/1.5.1/libexec/src/google/api (from $GOROOT)
    /Users/tmc/go/src/google/api (from $GOPATH)