Trac #21318: fixup due to recent changes in dependencies

Author: dkrenn

src/sage/combinat/recognizable_series.py

@@ -1403,7 +1403,7 @@ def __normalize__(cls,
                 'Coefficient ring {} is not a semiring.'.format(coefficient_ring))
 
         from sage.categories.modules import Modules
-        category = category or Modules(coefficients)
+        category = category or Modules(coefficient_ring)
 
         return (coefficient_ring, indices, category)