#383 taylor unhandled multivar datum comparison

[Stavros Macrakis]

taylor(x^y,x,0,1,y,0,1) and
taylor(taylor(x^y,y,0,1),x,0,1)
=>

Break: Unhandled multivar datum comparison

though

taylor(x^y,y,0,1,x,0,1);
=> 1+(LOG(x)+...)*y+...

and

TAYLOR(TAYLOR(x^y,x,0,1),y,0,1)
=> 1+(LOG(x)+...)*y+...

and

taylor(x^y,[x,y],[0,0],1);
= taylor(x^y,[y,x],[0,0],1);
=> 1+LOG(x)*y+...