adding flake to 18.03

Changelog: https://www.ruby-lang.org/en/news/2020/03/31/ruby-2-5-8-released/
(cherry picked from commit 99b09d6b8f201379bb34f01a1acacdc1c3950c46)

flake.nix

@@ -0,0 +1,48 @@
+# Experimental flake interface to Nixpkgs.
+# See https://github.com/NixOS/rfcs/pull/49 for details.
+{
+  description = "A collection of packages for the Nix package manager";
+
+  outputs = { self }:
+    let
+
+      jobs = import ./pkgs/top-level/release.nix {
+        nixpkgs = self;
+      };
+
+      lib = import ./lib;
+
+      systems = [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ];
+
+      forAllSystems = f: lib.genAttrs systems (system: f system);
+
+    in
+    {
+      lib = lib // {
+        nixosSystem = { modules, ... } @ args:
+          import ./nixos/lib/eval-config.nix (args // {
+            modules = modules ++
+              [ { system.nixos.versionSuffix =
+                    ".${lib.substring 0 8 (self.lastModifiedDate or self.lastModified)}.${self.shortRev or "dirty"}";
+                  system.nixos.revision = lib.mkIf (self ? rev) self.rev;
+                }
+              ];
+          });
+      };
+
+      checks.x86_64-linux.tarball = jobs.tarball;
+
+      htmlDocs = {
+        nixpkgsManual = jobs.manual;
+        nixosManual = (import ./nixos/release-small.nix {
+          nixpkgs = self;
+        }).nixos.manual.x86_64-linux;
+      };
+
+      legacyPackages = forAllSystems (system: import ./. { inherit system; });
+
+      nixosModules = {
+        notDetected = import ./nixos/modules/installer/scan/not-detected.nix;
+      };
+    };
+}

pkgs/development/interpreters/ruby/default.nix

@@ -207,18 +207,18 @@ in {
   };
 
   ruby_2_4 = generic {
-    version = rubyVersion "2" "4" "4" "";
+    version = rubyVersion "2" "4" "9" "";
     sha256 = {
-      src = "0nmfr2lijik6cykk0zbj11zcapcrvmdvq83k3r6q3k74g4d1qkr5";
-      git = "103cs7hz1v0h84lbrippl87s4lawi20m406rs5dgxl2gr2wyjpy5";
+      src = "1bn6n5b920qy3lsx99jr8495jkc3sg89swgb96d5fgd579g6p6zr";
+      git = "066kb1iki7mx7qkm10xhj5b6v8s47wg68v43l3nc36y2hyim1w2c";
     };
   };
 
   ruby_2_5 = generic {
-    version = rubyVersion "2" "5" "1" "";
+    version = rubyVersion "2" "5" "8" "";
     sha256 = {
-      src = "1c99k0fjaq7k09104h1b1cqx6mrk2b14ic1jjnxc6yav68i1ij6s";
-      git = "1j0fd16aq9x98n0kq9c3kfp2sh6xcsq8q4733p0wfqjh3vz50kyj";
+      src = "16md4jspjwixjlbhx3pnd5iwpca07p23ghkxkqd82sbchw3xy2vc";
+      git = "19gkk3q9l33cwkfsp5k8f8fipq7gkyqkqirm9farbvy425519rv2";
     };
   };
 }

pkgs/development/interpreters/ruby/patchsets.nix

@@ -11,12 +11,12 @@ rec {
     "${patchSet}/patches/ruby/2.3/head/railsexpress/02-improve-gc-stats.patch"
     "${patchSet}/patches/ruby/2.3/head/railsexpress/03-display-more-detailed-stack-trace.patch"
   ];
-  "2.4.4" = ops useRailsExpress [
+  "2.4.9" = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.4/head/railsexpress/01-skip-broken-tests.patch"
     "${patchSet}/patches/ruby/2.4/head/railsexpress/02-improve-gc-stats.patch"
     "${patchSet}/patches/ruby/2.4/head/railsexpress/03-display-more-detailed-stack-trace.patch"
   ];
-  "2.5.1" = ops useRailsExpress [
+  "2.5.8" = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.5/head/railsexpress/01-fix-broken-tests-caused-by-ad.patch"
     "${patchSet}/patches/ruby/2.5/head/railsexpress/02-improve-gc-stats.patch"
     "${patchSet}/patches/ruby/2.5/head/railsexpress/03-more-detailed-stacktrace.patch"

pkgs/development/libraries/ffmpeg/2.8.nix

@@ -1,7 +1,7 @@
 { callPackage, ... } @ args:
 
 callPackage ./generic.nix (args // rec {
-  version = "${branch}.14";
+  version = "${branch}.15";
   branch = "2.8";
-  sha256 = "1g6x3lyjl1zlfksizj1ys61kj97yg0xf4dlr6sr5acpbja3a26yn";
+  sha256 = "08gf493a1ici1rn6gda6bxkcsk3fqbs6pdr0phcifjkd3xn7yr1m";
 })