I’m not aware of anything and what I did to work around this problem was setting up a local IVY-repo to contain most of my deployments and make projects depend an that instead of using a composite build. In my case project A was providing Java-based plugins to make building, deploying etc. other projects easier and some of these plugins are not implemented in Java anymore at all, but using Groovy plugin-scripts instead. Those are then linked using svn:externals into consuming projects.
Don’t like these approaches too much as well, but using composite builds currently doesn’t seem to be well thought when it comes to upgrading the individual Gradle-wrappers of projects and stuff like that: