callr sets the repos option in subprocesses, to make sure that
a CRAN mirror is set up. This is because the subprocess cannot bring
up the menu of CRAN mirrors for the user to choose from.
default_repos()Named character vector, the default value of the repos
option in callr subprocesses.
default_repos()
#> RSPM
#> "https://packagemanager.posit.co/cran/__linux__/jammy/2024-10-06"
#> gh-pkg-mirror
#> "https://a2-ai.github.io/gh-pkg-mirror/2024-10-06"
#> CRAN
#> "https://cloud.r-project.org"