rotate_extrude changes with $fn even odd

rotang=360;     // [-400:10:400]
rotsta=  0;     // [-400:20:400]
rotfn =  0;     // [0:50]
rotgiv=true;

/* [Hidden] */
$fa=.5;
$fs=1;

module base_shape() {
    translate([4,4,0]){
            square(4);
        translate([4,4,0]*1.5)
            circle(4);
        }
    children();
    }
color("red")
    base_shape();
color("yellow")
    rotate([90,0,0]) base_shape();

if( rotgiv )
    %rotate_extrude( a=rotang, start=rotsta, $fn=rotfn )
        base_shape();
else
    %rotate_extrude( $fn=rotfn )
        base_shape();