Merge pull request #909 from buildkite/keithduncan/add-eager-concurrency

Enable eager concurrency

Author: keithduncan

.buildkite/pipeline.yml

@@ -118,6 +118,7 @@ steps:
       queue: "${BUILDKITE_AGENT_META_DATA_QUEUE}"
     concurrency_group: "aws-stack-publish"
     concurrency: 1
+    concurrency_method: eager
     artifact_paths: "build/*.yml"
     depends_on: "copy-ami"