Update nixos-unstable

arion-compose.cabal

@@ -24,6 +24,10 @@ data-files:          nix/*.nix
 -- all data is verbatim from some sources
 data-dir:            src
 
+source-repository head
+  type: git
+  location: https://github.com/hercules-ci/arion
+
 common common
   build-depends:     base >=4.12.0.0 && <4.15
                    , aeson

nix/haskell-overlay.nix

@@ -2,7 +2,7 @@ self: super: hself: hsuper:
 {
   arion-compose = import ./haskell-arion-compose.nix { pkgs = self; haskellPackages = hself; };
   arion-compose-checked =
-              let pkg = super.haskell.lib.buildStrictly hself.arion-compose;
+              let pkg = /* super.haskell.lib.buildStrictly  currently broken in nixos-unstable */ hself.arion-compose;
                   checked = super.haskell.lib.overrideCabal pkg (o: {
                     postConfigure = ''${o.postConfigure or ""}
                       if ! ${hsuper.cabal-install}/bin/cabal check;

nix/sources.json

@@ -36,15 +36,15 @@
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "nixos-unstable": {
-        "branch": "master",
+        "branch": "nixos-unstable",
         "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",
         "homepage": "https://github.com/NixOS/nixpkgs",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "97c3d70a39070547a8342f7ee6f5c4a560282179",
-        "sha256": "1pkagmf42n3v4bjk8jr23hcwpa5qy21w0psi0jbdrbsgpp6rchqa",
+        "rev": "c6c4a3d45ab200f17805d2d86a1ff1cc7ca2b186",
+        "sha256": "1f6q98vx3sqxcn6qp5vpy00223r9hy93w9pxq65h9gdwzy3w4qxv",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/97c3d70a39070547a8342f7ee6f5c4a560282179.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/c6c4a3d45ab200f17805d2d86a1ff1cc7ca2b186.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz",
         "version": ""
     },