nixpkgs/pkgs/desktops/gnome/core/dconf-editor/schema-override-variable.patch

diff --git a/editor/source-manager.vala b/editor/source-manager.vala
index 27b2b17a..87f7ba86 100644
--- a/editor/source-manager.vala
+++ b/editor/source-manager.vala
@@ -121,6 +121,9 @@ private class SourceManager : Object
             source = try_prepend_dir (source, Path.build_filename (system_data_dirs [i], "glib-2.0", "schemas"));
         string user_data_dir = GLib.Environment.get_user_data_dir ();
         source = try_prepend_dir (source, Path.build_filename (user_data_dir, "glib-2.0", "schemas"));
+        string? nix_var_schema_dir = GLib.Environment.get_variable ("NIX_GSETTINGS_OVERRIDES_DIR");
+        if (nix_var_schema_dir != null)
+            source = try_prepend_dir (source, (!) nix_var_schema_dir);
         string? var_schema_dir = GLib.Environment.get_variable ("GSETTINGS_SCHEMA_DIR");
         if (var_schema_dir != null) {
             string[] extra_schema_dirs = ((!) var_schema_dir).split (Path.SEARCHPATH_SEPARATOR_S);