Operating system and graphics card
Ubuntu 14.04 x64 Geforce 730M
Broken: 2.71 testbuild2
Short description of error
Behind completely transparent surfaces the noise pattern of volumes differs. It also takes a lot longer to clear up. For the example .blend and screenshot, even after 1000 samples there was noise left in the "Suzanne-Area". After 2.000 samples it had converged.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps.
Using the attached .blend: Turn on live preview or render.