DEVELOPMENT_BUILD define never set

I would like to compile-out a lot of C# test code in the release version of my game. I don't wan't to have to remember to change custom defines and I would like Unity Cloud Build to automatically do the right thing. I thought the best way was to use the "Development Build" checkbox in Build Settings. This is a test:

 #if DEVELOPMENT_BUILD
     ??? A
 #else
     ??? B
 #endif

I expected this code to get a compilation error at ??? A when "Development Build" is checked but this never happens. What is wrong? Is there another way to solve my need?

Here is the documentation: http://docs.unity3d.com/Manual/PlatformDependentCompilation.html

"You can also use the DEVELOPMENT_BUILD define to identify whether your script is running in a player which was built with the “Development Build” option enabled."

I'm using Unity 4.6.9 on Mac OS X 10.11.1