Bug report due to Hartmut Henkel in
>> [Ngspice-users] Noise analysis depends on ac parameter
The noise analysis internally depends on an ac analysis
to derive "inoise" from "onoise"
("onoise" is multiplied with the inverse ac gain from input to output)
This AC analysis used all the given ac magnitudes for all vsrc/isrc
devices in the deck.
This fix overrides all ac magnitudes with zero,
except for the given input device,
whose magnitude is set to one.
07ee771a96