Operating system and graphics card
Windows 7 Ultimate
GeForce GTX 780 Ti
i7-4770k CPU @ 3.50 GHz
Short description of error
There is a weird "flick" that change a bit the lighting for no reason.
Same file works normally on 2.69 but 2.70.5 and up its changing the light (although its mostly a HDR lighting).
Another thing is that the older version renders about 25% less time (Stamp with render time included on the attached frames).
Added 2 Blend files, and two sequences to show the change.
Weirdly, the 2.69 version renders normally in 2.7 but not the original version created with 2.7 itself
Download files (WeTransfer):
Exact steps for others to reproduce the error
Just open every file in its version and hit animation render (2 frames each)