Fix logic for determining pull request status on buildkite

build-tools-internal/src/main/groovy/elasticsearch.build-scan.gradle

@@ -105,7 +105,7 @@ buildScan {
 
       // Add SCM information
       def prId = System.getenv('BUILDKITE_PULL_REQUEST')
-      if (prId) {
+      if (prId != 'false') {
         def prBaseUrl = (System.getenv('BUILDKITE_PULL_REQUEST_REPO') - ".git")
         value 'Git Commit ID', System.getenv('BUILDKITE_COMMIT')
         tag "pr/${prId}"