liquidhaskell-boot-0.9.12.2.1

```
Test suite failure for package liquidhaskell-boot-0.9.12.2.1
ghc-api-tests: exited with: ExitFailure 1

CaseDesugaring.hs:1:8: error: [GHC-45102]
Ambiguous module name ‘Prelude’.
it was found in multiple packages:
atelier-prelude-0.2.0.0 base-4.21.2.0

4 out of 5 tests failed (1.93s)
```

cc @ulysses4ever

Start by reproducing the liquidhaskell-boot-0.9.12.2.1 test suite failure and inspect the ghc-api-tests case involving CaseDesugaring.hs. Determine why Prelude is found in both atelier-prelude-0.2.0.0 and base-4.21.2.0; done means the test suite no longer reports the ambiguous module and all five tests pass.

Written by the indexing model from the issue text.