rgba r,g,b values of 1 interpreted as 255
my_object = self.svg.selected[0]
my_object.style.set_color('rgba(0, 0, 0, 1)') -- Colour is black (fill:#000000)
my_object.style.set_color('rgba(1, 0, 0, 1)') or (0, 1, 0, 1) or (0, 0, 1, 1) -- results in fill:#ff0000 or fill:#00ff00 or fill:#0000ff
my_object.style.set_color('rgba(2, 0, 0, 1) etc -- results in correct fill:#020000
Inkscape 1.1 (1:1.1+202105261518+ce6663b3b7) Ubuntu 20.10