power series bug

[Igor Schein <igor@txc.com>]

Hi,

? (acos(y)+z)^1.;
  ***   Warning: normalizing a polynomial with 0 leading term.
  ***   Warning: normalizing a series with 0 leading term.
  ***   division by zero in gdiv, gdivgs or ginv

If I pre-introduce variable z to the stack, it works fine:

? z^2;(acos(y)+z)^1.;
? 

Thanks

Igor