1 files changed, 4 insertions, 2 deletions
diff --git a/app/services/ci/create_downstream_pipeline_service.rb b/app/services/ci/create_downstream_pipeline_service.rb
index a65c22e273c..a2e53cbf9b8 100644
--- a/app/services/ci/create_downstream_pipeline_service.rb
+++ b/app/services/ci/create_downstream_pipeline_service.rb
@@ -125,7 +125,9 @@ module Ci
           config_checksum(pipeline) unless pipeline.child?
         end
 
-        pipeline_checksums.uniq.length != pipeline_checksums.length
+        # To avoid false positives we allow 1 cycle in the ancestry and
+        # fail when 2 cycles are detected: A -> B -> A -> B -> A
+        pipeline_checksums.tally.any? { |_checksum, occurrences| occurrences > 2 }
       end
     end
 
@@ -137,7 +139,7 @@ module Ci
     end
 
     def config_checksum(pipeline)
-      [pipeline.project_id, pipeline.ref].hash
+      [pipeline.project_id, pipeline.ref, pipeline.source].hash
     end
   end
 end