set locale=en to fix locale leakage from other requests

app/controllers/diaspora_federation/application_controller.rb

@@ -1,5 +1,12 @@
 module DiasporaFederation
   # Base-Controller for all DiasporaFederation-Controller
   class ApplicationController < ActionController::Base
+    before_action :set_locale
+
+    # Fix locale leakage from other requests.
+    # Set "en" as locale for every federation request.
+    def set_locale
+      I18n.locale = :en
+    end
   end
 end

spec/controllers/diaspora_federation/application_controller_spec.rb

@@ -0,0 +1,16 @@
+module DiasporaFederation
+  describe ApplicationController, type: :controller do
+    controller do
+      def index
+        head :ok
+      end
+    end
+
+    describe "#set_locale" do
+      it "sets the default locale" do
+        expect(I18n).to receive(:locale=).with(:en)
+        get :index
+      end
+    end
+  end
+end