Computing density of a mixture of independent random variables gives runtime error

[matus.s...@privatdemail.net]

import sympy as sp
from sympy import stats
y,a1,a0,v=sp.symbols('y a1 a0 v',positive=True,real=True)
Y1=stats.Gamma('Y1',a1,v)
Y0=stats.Gamma('Y0',a0,v)
stats.density(sp.Min(Y1,Y0))
stats.density(Y1/Y0)

returns

RuntimeError: maximum recursion depth exceeded

The same for other operations between random variates and for other distributions. 

Why is sympy failing? As far as I'm aware these are problems with straightforward solution.