--- Operating System, Graphics card ---
Operating System: Windows 7 Home Premium 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.130104-1431)
Processor: Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz (4 CPUs), ~3.4GHz
Memory: 16384MB RAM
Graphics card name: NVIDIA GeForce GTX 670

--- Blender version with error, and version that worked ---
Blender version with error: 2.66.0 r54697
Last known good version of blender: 2.65.10 r54350

--- Short description of error ---

Behavior observed:
When compositing, the use of a math node removes all color information from the image.
e.g. When multiplying (using the Math node) the Diffuse direct render layer with the Diffuse color render layer, the resulting image is grey-scale.
This phenomenon occurs with other math operations as well as multiplication.

Note: it is possible to achieve the desired behavior but only by separating the image in the the RGB channels first, performing the math operation on each of the channels separably and then recombining the channels to form the correct image

Expected Behavior:
When multiplying two render layers together, I would expect the color information to be retained and used as part of the Math node operations and the output image should hold the relevant color information.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
1) Activate all render layers + compositing
2) Render a scene
3) Go to the compositor
4) Add a viewer
5) Attempt to multiply the Diffuse Direct channel with the Diffuse indirect channel
6) View the result and see that it is in grey-scale.

The attached blend file has a scene that exhibits this behaviour.