I have a tree that consists of a configuration for each branch on which continuous integration builds are run.
I also want the ability for users to create preflight (proof) builds, but not to have those builds show up in the same list as the CI builds (for statistics) or use the same version numbers.
To accomplish this, I have a sub-configuration off of each build for proof builds.

It is only on the proof builds that I want to prompt the user for local workspace information.
Currently the way to do this is to set the proof-build variables in my configuration to 'Don't prompt' and then override them in each of my proof build configurations.
This requires duplicating the prompt information multiple times.

It would be cleaner to set up the prompt information in the root, but only enable prompting if the configuration name == "proof".

This feature would enable other clever workflows as well, like 'only prompt for a milestone label if the build is being triggered by a member of the Release Engineering group'.