[Mathematica] Bug in Integrate with derivatives of a delta function

[Hepth]

Integrate[f[qs] DiracDelta'[qs (1 - 1/x)], {qs, -\[Infinity], \[Infinity]}, 
 Assumptions -> 0 < x < 1]
Integrate[f[qs] DiracDelta'[qs - qs/x], {qs, -\[Infinity], \[Infinity]}, 
 Assumptions -> 0 < x < 1]

This is on Mathematica 8 for windows.
The results differ by a sign. They are effective the exact same thing, but due to how I write the insides of the dirac delta I get a different result.

Can anyone replicate this?

 

[Hepth]

I notice it is only for the first negative power of x. If you put

[qs (1 - 1/x^(1.))]

[qs - qs/x^(1.)]

it works?