Qt4WebKit cleanup is coming, and versions <=sci-mathematics/rstudio-0.98.953 need to be cleaned up. Current stable is broken anyway (boost).
The pull request 5945 removing the old rstudio versions looks perfect, I'd love it if these old rstudio versions were dropped, thanks!
Cleanup done in git commit 679cc5c1a355784caac199f88a5dcfb84c6d6b06