A related bug is:
(%i2) integrate(x*exp(-x^2+b*x),x,0,inf);
"Is "b" positive, negative, or zero?"pos;
(%o2) -(gamma_incomplete(1/2,b^2/4)*%e^(b^2/4)*abs(b))/4+(sqrt(%pi)*b*%e^(b^2/4))/2+(gamma_incomplete(1,b^2/4)*%e^(b^2/4))/2
(%i3) integrate(x*exp(-x^2+b*x),x,0,inf);
"Is "b" positive, negative, or zero?"pos;
(%o3) -(gamma_incomplete(1/2,b^2/4)*b*%e^(b^2/4))/4+(sqrt(%pi)*b*%e^(b^2/4))/2+(gamma_incomplete(1,b^2/4)*%e^(b^2/4))/2
I think both answers are correct--the first has a term abs(b), but the second has just b. Maybe you could file a bug report.
--bw
________________________________