Is there a REST API for inspecting/manipulating build definitions?

I've been tearing my hair out trying to find a REST API for inspecting the details of a build definition. Specifically I want to get information about the Jazz SCM workspace that is being used by a particular build.

I have not been able to find this level of detail in any of the REST APIs I've found so far. The reportable REST API for build definitions does not include this level of detail. Using firebug to reverse engineer it doesn't work because the web UI does not have facilities for editing build definitions.

I can easily write a Java program to do what I want, but for this particular use case I would much prefer a script-based solution.