change construction and add doctest

Author: GiacomoPope

src/sage/schemes/hyperelliptic_curves/constructor.py

@@ -277,7 +277,13 @@ def is_pAdicField(x):
             cls_name.append(name)
             break
 
+    base_cls = None
+    if len(superclass) == 0:
+        base_cls = HyperellipticCurve_generic
+
     class_name = "_".join(cls_name)
-    cls = dynamic_class(class_name, tuple(superclass),
-                        HyperellipticCurve_generic, doccls=HyperellipticCurve)
+    cls = dynamic_class(class_name,
+                        tuple(superclass),
+                        cls=base_cls,
+                        doccls=HyperellipticCurve)
     return cls(PP, f, h, names=names, genus=g)

src/sage/schemes/hyperelliptic_curves/hyperelliptic_g2.py

@@ -45,6 +45,15 @@ def jacobian(self):
             sage: f = x^5 - x^4 + 3
             sage: HyperellipticCurve(f).jacobian()
             Jacobian of Hyperelliptic Curve over Rational Field defined by y^2 = x^5 - x^4 + 3
+
+        TESTS:
+
+        Ensure that :issue:`37612` is fixed::
+
+            sage: R.<x> = QQ[]
+            sage: f = x^5 - x^4 + 3
+            sage: HyperellipticCurve(f).jacobian
+            <bound method HyperellipticCurve_g2.jacobian of Hyperelliptic Curve over Rational Field defined by y^2 = x^5 - x^4 + 3>
         """
         return jacobian_g2.HyperellipticJacobian_g2(self)