Infinite sum wrong result. Bug in Giac?

[Helge Gabert]

Confirmed.

And, by the same token, sum from k=1 to infinity (((1-i)/2)^k) should return -i, but the Prime also thinks it is zero.

[Edit: Also checked sum from k=1 to infinity (((-1+i)/2)^k) should return -2/5+i/5, but the Prime returns -2/5.

Ditto sum from k=1 to infinity (((-1-i)/2)^k) should return -2/5-i/5, but the Prime returns -2/5 only.]