anchor.diff:  ARG STARGZ_SNAPSHOTTER_VERSION=v0.11.4
   ARG NERDCTL_VERSION=v0.17.1
   
  +# ALPINE_VERSION sets version for the base layers
   ARG ALPINE_VERSION=3.15
   
   # git stage is used for checking out remote repository sources
  
positive.code: # containerd v1.4 for integration tests
  FROM containerd-base as containerd-alt-14
  ARG CONTAINERD_ALT_VERSION_14
  ARG GO111MODULE=off
  RUN --mount=from=containerd-src,src=/usr/src/containerd,readwrite --mount=target=/root/.cache,type=cache \
    git fetch origin \
    && git checkout -q "$CONTAINERD_ALT_VERSION_14" \
  
negative.code: # containerd v1.5 for integration tests
  FROM containerd-base as containerd-alt-15
  ARG CONTAINERD_ALT_VERSION_15
  RUN --mount=from=containerd-src,src=/usr/src/containerd,readwrite --mount=target=/root/.cache,type=cache \
    git fetch origin \
    && git checkout -q "$CONTAINERD_ALT_VERSION_15" \
  