src/sage/schemes/elliptic_curves/constructor.py: Fix up

Author: Matthias Koeppe

src/sage/schemes/elliptic_curves/constructor.py

@@ -423,7 +423,7 @@ def create_key_and_extra_args(self, x=None, y=None, j=None, minimal_twist=True,
             x = x.lhs() - x.rhs()
 
         if isinstance(parent(x), sage.rings.abc.SymbolicRing):
-            x = x._polynomial_(rings.QQ['x', 'y'])
+            x = x._polynomial_(QQ['x', 'y'])
 
         if isinstance(x, MPolynomial):
             if y is None: