jobs/build-kola-containers: Call skopeo from cosa

The skopeo call to check for changes was running outside of cosa
where the binary is not available. This only started to cause issues
recently somehow

jobs/build-kola-containers.Jenkinsfile

@@ -97,32 +97,6 @@ node {
         cd ${path}
         find . -maxdepth 1 -mindepth 1 -type d -exec basename {} \\;
     """).trim().split("\n")
-
-    if ( !params.FORCE ) {
-        // get the git commit ref for the last built container
-        def previous_ref = shwrapCapture("""
-            skopeo inspect --no-creds docker://${params.CONTAINER_REGISTRY_ORG}/${contexts[0]}:latest \
-            | jq -r '.Labels.org.opencontainers.image.revision'
-        """)
-
-        // Check for changes in tests/containers/* since the last build
-        // If none, no need to run this
-        changeset = shwrapRc("git diff --quiet ${previous_ref} -- ${path}")
-    } else {
-        changeset = 1
-  }
-}
-
-if ( changeset == 0 ) {
-    currentBuild.result = 'SUCCESS'
-    currentBuild.description = "[${gitref}@${shortcommit}] 💤 (no change)."
-    return
-} else if ( changeset != 1 ) {
-    currentBuild.result = 'FAILURE'
-    currentBuild.description = "[${gitref}@${shortcommit}] ❌ Cannot determine changes. git diff return code ${changeset}."
-    message = "build-kola-test-containers #${env.BUILD_NUMBER} <${env.BUILD_URL}|:jenkins:> <${env.RUN_DISPLAY_URL}|:ocean:> [${gitref}@${shortcommit}]"
-    pipeutils.trySlackSend(message: message)
-    return
 }
 
 currentBuild.description = "[${gitref}@${shortcommit}] Waiting"
@@ -139,6 +113,34 @@ lock(resource: "build-kola-containers") {
     timeout(time: 60, unit: 'MINUTES') {
     try {
 
+        if ( !params.FORCE ) {
+            // get the git commit ref for the last built container
+            def previous_ref = shwrapCapture("""
+                skopeo inspect --no-creds docker://${params.CONTAINER_REGISTRY_ORG}/${contexts[0]}:latest \
+                | jq -r '.Labels.org.opencontainers.image.revision'
+            """)
+
+            // Check for changes in tests/containers/* since the last build
+            // If none, no need to run this
+            def path = params.PATH_TO_CONTEXTS
+            changeset = shwrapRc("git diff --quiet ${previous_ref} -- ${path}")
+
+        } else {
+            changeset = 1
+        }
+
+        if ( changeset == 0 ) {
+            currentBuild.result = 'SUCCESS'
+            currentBuild.description = "[${gitref}@${shortcommit}] 💤 (no change)."
+            return
+        } else if ( changeset != 1 ) {
+            currentBuild.result = 'FAILURE'
+            currentBuild.description = "[${gitref}@${shortcommit}] ❌ Cannot determine changes. git diff return code ${changeset}."
+            message = "build-kola-test-containers #${env.BUILD_NUMBER} <${env.BUILD_URL}|:jenkins:> <${env.RUN_DISPLAY_URL}|:ocean:> [${gitref}@${shortcommit}]"
+            pipeutils.trySlackSend(message: message)
+            return
+        }
+
         currentBuild.description = "[${gitref}@${shortcommit}] Running"
 
         // By default we will allow re-using cache layers for one day.