Can't get repos on R 4.5 if Bioconductor is unreachable

[krlmlr]

In a situation where Bioconductor can't be reached and pkgcache doesn't know about the default Bioconductor version (R 4.5 at the time of writing), pak can't be used at all, even with Bioconductor turned off.

Sys.setenv("http_proxy" = "0.0.0.0:9")
Sys.setenv("https_proxy" = "0.0.0.0:9")

pkgcache::repo_get(bioc = FALSE)
#> Error in download.file(url, tmp, quiet = TRUE): cannot open URL 'http://bioconductor.org/config.yaml'

^{Created on 2025-08-31 with reprex v2.1.1}

I can work around by setting R_BIOC_VERSION to 3.21 -- the reprex works, pak works. With R < 4.5, the problem doesn't occur because this code path isn't hit:

Sys.setenv("http_proxy" = "0.0.0.0:9")
Sys.setenv("https_proxy" = "0.0.0.0:9")
Sys.setenv("R_BIOC_VERSION" = 3.21)

pkgcache::repo_get(bioc = FALSE)
#> # A data frame: 1 × 5
#>   name  url                         type  r_version bioc_version
#> * <chr> <chr>                       <chr> <chr>     <chr>       
#> 1 CRAN  https://p3m.dev/cran/latest cran  *         <NA>

^{Created on 2025-08-31 with reprex v2.1.1}

Is this one of the rare cases where a warning is appropriate? The bioc_names in cmc__get_repos() is for information only.

Also, should the failure to retrieve BioConductor's config be recorded so that it's not retried again? In my case, the proxy comes back only after 10 seconds.

Code reference:

pkgcache/R/metadata-cache.R

Line 1043 in 8ab7812

bioc_names <- bioconductor$get_repos()