withr_with_temp_libpaths causes dir.create error for multiple .libPaths #217

There seems to be a bug when .libPaths is not a single directory.

Building the package still works:
pkgbuild:::rcmd_build_tools("build", c("E:\\Steffi\\test", c("--no-resave-data" ,"--no-manual")), wd = "C:\\Users\\myName\\AppData\\Local\\Temp\\18\\RtmpKshZRc\\file59347b141e29", fail_on_status = TRUE, required = FALSE, quiet = quiet)

But building it with temportary libpaths doesn't:
pkgbuild:::withr_with_temp_libpaths( pkgbuild:::rcmd_build_tools("build", c("E:\\Steffi\\test", c("--no-resave-data" ,"--no-manual")), wd = "C:\\Users\\myName\\AppData\\Local\\Temp\\18\\RtmpKshZRc\\file59347b141e29", fail_on_status = TRUE, required = FALSE, quiet = quiet) )

The error is
In dir.create(Sys.getenv("R_LIBS_USER"), recursive = TRUE) :
cannot create dir 'C:\Users\myName\AppData\Local\Temp\18\RtmpKshZRc\temp_libpath593477b81f6d;C:\Program Files', reason 'Invalid argument'

Appearantly, the multiple directories in .libPaths are concatenated (with a semicolong separtor).

https://forum.posit.co/t/devtools-check/208755