edUnstable: init at 1.20-pre2

pkgs/applications/editors/ed/default.nix

···
     };
 
     ed = callPackage (self.sources.ed) { };
+    edUnstable = callPackage (self.sources.edUnstable) { };
   })

pkgs/applications/editors/ed/sources.nix

···
   in import ./generic.nix {
     inherit pname version src meta;
   };
+
+  edUnstable = let
+    pname = "ed";
+    version = "1.20-pre2";
+    src = fetchurl {
+      url = "http://download.savannah.gnu.org/releases/ed/ed-${version}.tar.lz";
+      hash = "sha256-bHTDeMhVNNo3qqDNoBNaBA+DHDa4WJpfQNcTvAUPgsY=";
+    };
+  in import ./generic.nix {
+    inherit pname version src meta;
+  };
 }

pkgs/top-level/all-packages.nix

···
   ecs-agent = callPackage ../applications/virtualization/ecs-agent { };
 
   inherit (recurseIntoAttrs (callPackage ../applications/editors/ed { }))
-    ed;
+    ed edUnstable;
 
   edbrowse = callPackage ../applications/editors/edbrowse { };