This is a workaround (https://github.com/moby/moby/issues/10180#issuecomment-190429512) the docker issue (https://github.com/moby/moby/issues/10180) which breaks protoc-artifacts build process with following error

```Rpmdb checksum is invalid: dCDPT(pkg checksums): devtoolset-1.1-elfutils.x86_64 0:0.154-6.el6 - u

The command '/bin/sh -c yum clean all && yum install -y devtoolset-1.1                    devtoolset-1.1-libstdc++-devel                    devtoolset-1.1-libstdc++-devel.i686' returned a non-zero code: 1```

https://github.com/moby/moby/issues/10180#issuecomment-190429512