Fix synchronising github and azure pipelines by SHA (#4768)

Co-authored-by: Amaury Chamayou <amchamay@microsoft.com>

.azure-pipelines-templates/deploy_aci.yml

@@ -16,10 +16,15 @@ jobs:
       - script: |
           set -ex
           RETRIES=500
-          LAST_COMMIT=(`git log -1 --pretty=%B`)
-          GIT_SHA=${LAST_COMMIT[1]}
-          echo "##vso[task.setvariable variable=gitSha;isOutput=true]$GIT_SHA"
-          until [ $RETRIES -eq 0 ] || [[ `az acr repository show-tags -n ccfmsrc --repository ccf/ci` == *"$GIT_SHA"* ]]
+          HEAD_SHA=`git rev-parse HEAD`
+          if [ -n $(System.PullRequest.PullRequestId) ]; then
+            # If this is the case, we're running in a PR, and the SHA we really want is in the
+            # commit message of the last commit (which merges it into target)
+            LAST_COMMIT=(`git log -1 --pretty=%B`)
+            HEAD_SHA=${LAST_COMMIT[1]}
+          fi
+          echo "##vso[task.setvariable variable=gitSha;isOutput=true]$HEAD_SHA"
+          until [ $RETRIES -eq 0 ] || [[ `az acr repository show-tags -n ccfmsrc --repository ccf/ci` == *"$HEAD_SHA"* ]]
           do
             sleep 10
             echo "$(( RETRIES-- )) tries remaining"

.github/workflows/build-ci-container.yml

@@ -44,7 +44,7 @@ jobs:
         run: docker pull $ACR_REGISTRY/ccf/ci:oe-0.18.4-hspec-snp
 
       - name: Build CCF CI SNP container
-        run: docker build -f docker/ccf_ci_built . --build-arg="base=ccfmsrc.azurecr.io/ccf/ci:oe-0.18.4-hspec" --build-arg="platform=snp" -t $ACR_REGISTRY/ccf/ci:pr-${{ github.event.pull_request.head.sha }}
+        run: docker build -f docker/ccf_ci_built . --build-arg="base=ccfmsrc.azurecr.io/ccf/ci:oe-0.18.4-hspec" --build-arg="platform=snp" -t $ACR_REGISTRY/ccf/ci:pr-`git rev-parse HEAD`
 
       - name: Push CI container
-        run: docker push $ACR_REGISTRY/ccf/ci:pr-${{ github.event.pull_request.head.sha }}
+        run: docker push $ACR_REGISTRY/ccf/ci:pr-`git rev-parse HEAD`