Support file+noindex repositories

[TeofilC]

Cabal's file+noindex repos are an alternative to source-repo-packages. I'm currently trying to figure out if these would be faster than using source-repo-packages with haskell.nix.

But it seems like haskell.nix's plan creation logic can't handle file+noindex repositories. We get errors like the following:

Warning: unable to update the repo index cache --
/nix/store/qqafdyqp0vx6rwd3qi388h1zwqixww5d-dot-cabal/packages/ch-overrides-7dac215512b0f397:
createDirectory: permission denied (Permission denied)
Warning: Error during construction of local+noindex ch-overrides repository
index:
/nix/store/qqafdyqp0vx6rwd3qi388h1zwqixww5d-dot-cabal/packages/ch-overrides-7dac215512b0f397/noindex.cache:
openBinaryFile: does not exist (No such file or directory)
Resolving dependencies...

It seems like we need to give it a space to write the cache

[TeofilC]

This is the probelmatic bit

haskell.nix/lib/cabal-project-parser.nix

Line 133 in 4b15770

parseRepositoryBlock = evalPackages: _cabalProjectFileName: sha256map: inputMap: nix-tools: block: