versioned package installation can fail when package provided by multiple repositories

[kevinushey]

For example:

options(repos = c("https://posit-dev.r-universe.dev", "https://cran.rstudio.com"))
remotes <- "mcptools@0.1.1"
pak::pkg_install(remotes)

This fails with:

> options(repos = c("https://posit-dev.r-universe.dev", "https://cran.rstudio.com"))
> remotes <- "mcptools@0.1.1"
> pak::pkg_install(remotes)
Error: 
! error in pak subprocess
Caused by error: 
! Could not solve package dependencies:
* mcptools@0.1.1: Conflicts with mcptools@0.1.1
Type .Last.error to see the more details.

And indeed:

> db <- available.packages(filters = "R_version")
> db[db[, "Package"] == "mcptools", 1:2]
         Package    Version     
mcptools "mcptools" "0.1.1.9000"
mcptools "mcptools" "0.1.1"    

[gadenbuie]

A long time ago, I opened an issue in remotes requesting a way to indicate that a specific package should be installed from a specific r-universe repository. While I think in this case, there is one version that satisfies the version requirement, I think there might be some conceptual overlap with that original request.