emacsPackages: make magithub a shared override

pkgs/applications/editors/emacs-modes/melpa-packages.nix

@@ -170,6 +170,12 @@ env NIXPKGS_ALLOW_BROKEN=1 nix-instantiate --show-trace ../../../../ -A emacsPac
             (attrs.nativeBuildInputs or []) ++ [ external.git ];
         });
 
+        magithub = super.magithub.overrideAttrs (attrs: {
+          # searches for Git at build time
+          nativeBuildInputs =
+            (attrs.nativeBuildInputs or []) ++ [ external.git ];
+        });
+
       kubernetes = super.kubernetes.overrideAttrs (attrs: {
         # searches for Git at build time
         nativeBuildInputs =
@@ -396,12 +402,6 @@ env NIXPKGS_ALLOW_BROKEN=1 nix-instantiate --show-trace ../../../../ -A emacsPac
           };
         });
 
-        magithub = super.magithub.overrideAttrs (attrs: {
-          # searches for Git at build time
-          nativeBuildInputs =
-            (attrs.nativeBuildInputs or []) ++ [ external.git ];
-        });
-
         magit-svn = super.magit-svn.overrideAttrs (attrs: {
           # searches for Git at build time
           nativeBuildInputs =