Jacobians should not be computed only for transforms

GPy/core/parameterization/parameter_core.py

@@ -457,6 +457,7 @@ class Indexable(Nameable, Updateable):
         #add in jacobian derivatives if transformed
         priored_indexes = np.hstack([i for p, i in self.priors.items()])
         for c,j in self.constraints.items():
+            if not isinstance(c, Transformation):continue
             for jj in j:
                 if jj in priored_indexes:
                     ret[jj] += c.log_jacobian_grad(x[jj])