message: fix: handle symlink to directory other than a local subdirectory
  If the charts symlink is pointing somewhere other than a subdirectory of
  the local lagoon working tree then readlink gets confused. The problem
  is described here, which is also where I got the solution:
diff: @@ -770,8 +770,8 @@ kind/retest:
  && export IMAGE_REGISTRY="registry.$$(./local-dev/kubectl get nodes -o jsonpath='{.items[0].status.addresses[0].address}').nip.io:32080/library" \
  && cd lagoon-charts.kind.lagoon \
  && $(MAKE) fill-test-ci-values TESTS=$(TESTS) IMAGE_TAG=$(SAFE_BRANCH_NAME) \
  - HELM=$$(realpath ../local-dev/helm) KUBECTL=$$(realpath ../local-dev/kubectl) \
  - JQ=$$(realpath ../local-dev/jq) \
  + HELM=$$(cd .. && realpath ./local-dev/helm) KUBECTL=$$(cd .. && realpath ./local-dev/kubectl) \
  + JQ=$$(cd .. && realpath ./local-dev/jq) \
  OVERRIDE_BUILD_DEPLOY_DIND_IMAGE=$$IMAGE_REGISTRY/kubectl-build-deploy-dind:$(SAFE_BRANCH_NAME) \
  IMAGE_REGISTRY=$$IMAGE_REGISTRY \
  SKIP_ALL_DEPS=true \
  @@ -781,7 +781,7 @@ kind/retest:
  && docker run --rm --network host --name ct-$(CI_BUILD_TAG) \
  --volume "$$(pwd)/test-suite-run.ct.yaml:/etc/ct/ct.yaml" \
  --volume "$$(pwd):/workdir" \
  - --volume "$$(realpath ../kubeconfig.kind.$(CI_BUILD_TAG)):/root/.kube/config" \
  + --volume "$$(cd .. && realpath ./kubeconfig.kind.$(CI_BUILD_TAG)):/root/.kube/config" \
  --workdir /workdir \
  "quay.io/helmpack/chart-testing:$(CHART_TESTING_VERSION)" \
  ct install
  