New problems in this space as of today. This time with
```bash
stack --stack-yaml stack.yaml --resolver nightly-2020-01-08 exec -- pacman -S autoconf automake-wrapper make patch python tar mintty --noconfirm
```
which produces 404 errors
```
2020-11-01T16:02:47.2564782Z :: Retrieving packages...
2020-11-01T16:02:49.0237771Z error: failed retrieving file 'diffutils-3.6-1-x86_64.pkg.tar.xz' from repo.msys2.org : The requested URL returned error: 404
2020-11-01T16:02:49.3752086Z error: failed retrieving file 'diffutils-3.6-1-x86_64.pkg.tar.xz' from downloads.sourceforge.net : The requested URL returned error: 404
2020-11-01T16:02:49.8476086Z error: failed retrieving file 'diffutils-3.6-1-x86_64.pkg.tar.xz' from www2.futureware.at : The requested URL returned error: 404
2020-11-01T16:02:49.8482030Z warning: failed to retrieve some files
2020-11-01T16:02:51.2288388Z error: failed retrieving file 'autoconf-2.69-3-any.pkg.tar.xz' from repo.msys2.org : The requested URL returned error: 404
2020-11-01T16:02:51.3674499Z error: failed retrieving file 'autoconf-2.69-3-any.pkg.tar.xz' from downloads.sourceforge.net : The requested URL returned error: 404
2020-11-01T16:02:51.4787091Z error: failed retrieving file 'autoconf-2.69-3-any.pkg.tar.xz' from www2.futureware.at : The requested URL returned error: 404
2020-11-01T16:02:51.4791763Z warning: failed to retrieve some files
...
```
I've raised https://github.com/msys2/MSYS2-packages/issues/2225 with msys2.