MuPAD heaviside in R2015a

Hi,

I'm trying to solve the following ode in MuPAD:

ode( {y''(t)+6*y'(t)+5*y(t)-heaviside(t-1)=0, y(0)=0, y'(0)=1 }, y(t) )

In 2015a, I get the following result:

{exp(-t)/4 - exp(-5*t)/4 - (exp(-t)*(sign(t - 1)/2 + 1/2)*(exp(1) - exp(t)))/4 - (exp(-5*t)*(sign(t - 1)/2 + 1/2)*(exp(5*t) - exp(5)))/20}

It's a little hard to read, but I'm getting sign() in place of heaviside(). R2014a does not have this problem. I get heaviside() as expected.

Did something change between R2014a and R2015a with regards to solving ODEs and heavside?

Thanks!