### I don't know why Sage return 0 for ~~integrate(sin(2*x).abs(),(x,0,2*pi)) ~~integrate(sin(2*x).abs(),(x,0,pi)) when its value is 2

When I try ~~integrate(sin(x).abs(),(x,0,2*pi)) ~~integrate(sin(x).abs(),(x,0,pi)) the program return the same value. The numerical integration is correct, the program return (1.9999999999999998, 2.220446049250313e-14). I don't know if it is a bug or what. Any help? I have tried sage 6.2, 6.3, 6.4.1

Mathematica can do It without any problem http://www.wolframalpha.com/input/?i=Integrate[Abs[Sin[2*x]]%2C{x%2C0%2CPi}]

Neither Sympy nor Maxima can't compute this.