WIP: Make local packages override source packages from the repository

I am not sure about this commit. This works by package name and not by package id like hideInstalledPackagesSpecificBySourcePackageId.

Author: andreabedini

cabal-install/src/Distribution/Client/Dependency.hs

@@ -476,8 +476,8 @@ addSourcePackages
 addSourcePackages pkgs params =
   params
     { depResolverSourcePkgIndex =
-        foldl
-          (flip PackageIndex.insert)
+        foldl'
+          (\idx pkg -> PackageIndex.insert pkg $ PackageIndex.deletePackageName (packageName pkg) idx)
           (depResolverSourcePkgIndex params)
           pkgs
     }