Query the main 'R' 'SVN' repository to find the versions 'r-release' and 'r-oldrel' refer to, and also all previous 'R' versions and their release dates.
copied from cf-staging / r-rversions
https://anaconda.org/conda-forge/r-rversions/badges/version.svg
https://anaconda.org/conda-forge/r-rversions/badges/latest_release_date.svg
https://anaconda.org/conda-forge/r-rversions/badges/latest_release_relative_date.svg
https://anaconda.org/conda-forge/r-rversions/badges/platforms.svg
https://anaconda.org/conda-forge/r-rversions/badges/license.svg
https://anaconda.org/conda-forge/r-rversions/badges/downloads.svg