Interpret Nested Variables in Subversion URL

See groups thread here:

http://groups.google.com/group/jenkinsci-users/browse_frm/thread/5bb278d41fd97021/8a3f468c47b971f6?#8a3f468c47b971f6

I'm trying to create a pipeline for my build process. The same steps will be executed, but against different subversion branches and/or data sources.

For most areas I am using the "run script" build step, so I can do something like this:

eval \$RELEASE_BRANCH_$STACK

Where STACK=03 and RELEASE_BRANCH_03=http://server:port/repository/branches/03_BRANCH (the svn URL for the 03 release branch). The eval command won't work in that field. I'd like this sort of support, simular to the SSH plugins.

Thanks!