Since xanthous has a checked-in package.yaml and cabal file, the
haskellPackages build infrastructure will use the package.yaml file for
all builds. The resulting problem is that our CI won't actually catch build
failures that would be observable with cabal or when building from the
sdist.
We fix that by filtering out the package.yaml file in pkg.nix
additionally to the filters specified in .gitignore. For this we need
gitignoreFilter from gitignore.nix which we expose as part of a functor
set from third_party.gitignoreSource to maintain interface
compatibility.
Change-Id: I337185f484d2027341f38031dcd78898706904eb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2609
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
Reviewed-by: tazjin <mail@tazj.in>
1799ddf7f0
