stop automatic collation if the sequence of numbers doesn't seem to be indices in an ordering

dlibrary/dlibrary.py

@@ -212,6 +212,9 @@ def complete_prefix_number_ordering(entries):
     unified_indices = list(unified_indices)
     unified_indices.sort()
 
+    if len(unified_indices) > 1 and min(unified_indices[i] - unified_indices[i-1] for i in range(1, len(unified_indices))) > 2:
+        return None
+
     versions = list(numberings_by_version.keys())
     versions.sort()