diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -200,6 +200,7 @@
         for alias in unresolved_aliases:
             branches[alias] = draw(branch_targets(only_objects=True))
 
+    # Ensure no cycles between aliases
     while True:
         try:
             id_ = snapshot_identifier({