wine: Get rid of overcomplicated overrride dance in default.nix

The new logic is much easier to read, and (I hope!) better documented.

As an added bonus, replace with the `with src` with a more targeted `let
inherit`.

pkgs/applications/emulators/wine/default.nix

@@ -49,10 +49,10 @@
 
 let
   wine-build =
-    build: release:
+    build:
     lib.getAttr build (
       callPackage ./packages.nix {
-        wineRelease = release;
+        inherit wineRelease;
         supportFlags = {
           inherit
             alsaSupport
@@ -91,18 +91,5 @@ let
         inherit moltenvk;
       }
     );
-
-  baseRelease =
-    {
-      staging = "unstable";
-      yabridge = "yabridge";
-    }
-    .${wineRelease} or null;
 in
-if baseRelease != null then
-  (wine-build wineBuild baseRelease).override {
-    inherit wineRelease;
-    useStaging = true;
-  }
-else
-  wine-build wineBuild wineRelease
+wine-build wineBuild

pkgs/applications/emulators/wine/packages.nix

@@ -18,9 +18,27 @@
 }:
 
 let
-  src = lib.getAttr wineRelease (callPackage ./sources.nix { });
+  sources = callPackage ./sources.nix { };
+
+  # "staging" of course enables staging, but for "yabridge" we do too
+  # --- we are not interested in yabridge without the staging patches
+  # applied.
+  useStaging = wineRelease == "staging" || wineRelease == "yabridge";
+
+  # Map wineRelease to actual source. Many versions have a "staging"
+  # variant, but when we say "staging", the version we want to use is
+  # "unstable".
+  baseRelease = if wineRelease == "staging" then "unstable" else wineRelease;
+
+  src = lib.getAttr baseRelease (callPackage ./sources.nix { });
+  inherit (src)
+    version
+    patches
+    gecko32
+    gecko64
+    mono
+    ;
 in
-with src;
 {
   wine32 = pkgsi686Linux.callPackage ./base.nix {
     pname = "wine";
@@ -31,6 +49,7 @@ with src;
       patches
       moltenvk
       wineRelease
+      useStaging
       # Forcing these `nativeBuildInputs` used in the `staging` to come
       # from ambient `pkgs`, rather than being provided by
       # `pkgsi686Linux.callPackage` for that platform.
@@ -58,6 +77,7 @@ with src;
       patches
       moltenvk
       wineRelease
+      useStaging
       ;
     pkgArches = [ pkgs ];
     mingwGccs = with pkgsCross; [ mingwW64.buildPackages.gcc ];
@@ -79,6 +99,7 @@ with src;
       patches
       moltenvk
       wineRelease
+      useStaging
       ;
     stdenv = stdenv_32bit;
     pkgArches = [
@@ -112,6 +133,7 @@ with src;
       patches
       moltenvk
       wineRelease
+      useStaging
       ;
     supportFlags = supportFlags // {
       mingwSupport = true;