[R-SIG-Mac] contrib.url(type = 'mac.binary')

[Jeroen Ooms]

The R-admin manual section 6.6 talks about "mac.binary" to refer to
macos binary packages but I don't think this is working. On R-4.4.2:

  contrib.url(repos = 'https://cran.r-project.org', type = 'mac.binary')
  # "https://cran.r-project.org/bin/macosx/contrib/4.4"

This URL is 404 because it is missing the /big-sur-arm64/ dir in the
path. For the same reason we get an error:

   install.packages('MASS', type = 'mac.binary')

I think in practice only type = "both" currently finds the correct
binary packages?