FIX: Clear uploads cache on `SiteSetting.refresh!`.

This fixes a bug where the return value of uploads site settings
may defer between processes even though we trigger a refresh via
MessageBus.

lib/site_setting_extension.rb

@@ -269,8 +269,16 @@ module SiteSettingExtension
       shadowed_settings.each { |ss| new_hash[ss] = GlobalSetting.send(ss) }
 
       changes, deletions = diff_hash(new_hash, current)
-      changes.each   { |name, val| current[name] = val }
-      deletions.each { |name, _|   current[name] = defaults_view[name] }
+
+      changes.each do |name, val|
+        current[name] = val
+        clear_uploads_cache(name)
+      end
+
+      deletions.each do |name, _|
+        current[name] = defaults_view[name]
+        clear_uploads_cache(name)
+      end
 
       clear_cache!
     end
@@ -318,7 +326,7 @@ module SiteSettingExtension
   def remove_override!(name)
     provider.destroy(name)
     current[name] = defaults.get(name, default_locale)
-    uploads.delete(name)
+    clear_uploads_cache(name)
     clear_cache!
   end
 
@@ -326,7 +334,7 @@ module SiteSettingExtension
     val, type = type_supervisor.to_db_value(name, val)
     provider.save(name, val, type)
     current[name] = type_supervisor.to_rb_value(name, val)
-    uploads.delete(name)
+    clear_uploads_cache(name)
     notify_clients!(name) if client_settings.include? name
     clear_cache!
   end
@@ -480,6 +488,12 @@ module SiteSettingExtension
     @uploads[provider.current_site] ||= {}
   end
 
+  def clear_uploads_cache(name)
+    if type_supervisor.get_type(name) == :upload && uploads.has_key?(name)
+      uploads.delete(name)
+    end
+  end
+
   def logger
     Rails.logger
   end

spec/components/site_setting_extension_spec.rb

@@ -133,6 +133,24 @@ describe SiteSettingExtension do
       settings.foo = "baz"
       expect(settings.foo).to eq("baz")
     end
+
+    it "clears the cache for site setting uploads" do
+      settings.setting(:upload_type, "", type: :upload)
+      upload = Fabricate(:upload)
+      settings.upload_type = upload
+
+      expect(settings.upload_type).to eq(upload)
+      expect(settings.send(:uploads)[:upload_type]).to eq(upload)
+
+      upload2 = Fabricate(:upload)
+      settings.provider.save(:upload_type, upload2.id, SiteSetting.types[:upload])
+
+      expect do
+        settings.refresh!
+      end.to change { settings.send(:uploads)[:upload_type] }.from(upload).to(nil)
+
+      expect(settings.upload_type).to eq(upload2)
+    end
   end
 
   describe "multisite" do