ghc/ghc#18774 points out that recent msys2 `gcc` builds (namely `10.1.0` used by https://gitlab.haskell.org/ghc/win32-tarballs/-/tags/0.2) include `D:` paths in the search path. This breaks on machines with optical storage devices without media. We need to ask `msys2` upstream to correct their build process and add a check in our CI infrastructure to ensure that the issue doesn't sneak in again.