grpcio 0.4.2

The rust language implementation of gRPC, base on the gRPC c core library.
#!/usr/bin/env bash
git submodule update --init grpc-sys/grpc
cd grpc-sys/grpc
git submodule update --init third_party/boringssl
git submodule update --init third_party/cares/cares
git submodule update --init third_party/zlib
cd third_party/zlib
git clean -f
git reset --hard