anchor.diff:  
   ENV PATH="/go/bin:/usr/local/go/bin:${PATH}" \
   	GOPATH="/go:${GOPATH}" \
  -	SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt \
  -    PKG_CONFIG_PATH="/usr/lib/pkgconfig/:/usr/local/lib/pkgconfig/:/usr/local/lib/libgit2/lib/pkgconfig:/usr/local/lib/openssl/lib/pkgconfig:/usr/local/lib/libssh2"
  +	SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
  +
   
   # install go and dep
  -RUN curl -fsSL "https://storage.googleapis.com/golang/go${go_version}.linux-amd64.tar.gz" | tar -xzC /usr/local \
  +RUN which go  || (curl -fsSL "https://storage.googleapis.com/golang/go${go_version}.linux-amd64.tar.gz" | tar -xzC /usr/local) \
       && mkdir -p /go/bin \
       && mkdir -p /go/src \
       && curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
  +
   
   COPY . .
   
   ## download deps & move libgit2 library into expected location.
   RUN git --version \
       && dep ensure \
  -	&& mkdir -p /go/src/github.com/analogj/capsulecd/vendor/gopkg.in/libgit2/git2go.v25/vendor/libgit2/build \
  -	&& cp -r /usr/local/lib/libgit2/lib/pkgconfig/. /go/src/github.com/analogj/capsulecd/vendor/gopkg.in/libgit2/git2go.v25/vendor/libgit2/build/ \
  +	&& mkdir -p vendor/gopkg.in/libgit2/git2go.v25/vendor/libgit2/build/ \
  +    && cp -r /usr/local/linux/lib/pkgconfig/. /go/src/github.com/analogj/capsulecd/vendor/gopkg.in/libgit2/git2go.v25/vendor/libgit2/build/ \
  +    && . /scripts/toolchains/linux/linux-build-env.sh \
   	&& ./ci/test-build.sh ${engine_type}
   
   ##################################################
  
positive.code: # Install build tooling.
  RUN echo "go version: $go_version" \
      && apt-get update \
  	&& apt-get install -y gcc git build-essential binutils curl apt-transport-https ca-certificates pkg-config zlib1g-dev --no-install-recommends \
  	&& rm -rf /usr/share/doc && rm -rf /usr/share/man \
  	&& rm -rf /var/lib/apt/lists/* \
      && apt-get clean
  
negative.code: ARG engine_type="golang"
  FROM analogj/libgit2-xgo:slim as base
  
  ARG go_version=1.10.8
  ARG engine_type="golang"
  