Similar limits give very different behavior

edit

sage: from sympy import Symbol, limit
sage: h=Symbol('h')
sage: limit((sin((pi+h)^2)-sin(pi^2))/h,h,0)
2*pi*cos(pi**2)

For what it's worth, Maxima is the one causing the hang.

(%i1) limit( (sin((h + x)^2) - sin(x^2))/h, h, 0);
                                       2
(%o1)                             2 x cos(x )

(%i3) limit( (sin((%pi+h)^2)-sin(%pi^2))/h,h,0);

But I can't diagnose it any further than that. Replacing %pi with 2 or something does the same (well, unless x=0).