Leave tag rules spec in clean state

spec/features/admin/tag_rules_spec.rb

@@ -231,6 +231,13 @@ feature 'Tag Rules', js: true do
         end
         expect(page).to have_no_selector "#tr_0"
       end.to change{ TagRule.count }.by(-2)
+
+      # After deleting tags, the form is dirty and we need to confirm leaving
+      # the page. If we don't do it here, Capybara may timeout waiting for the
+      # confirmation while resetting the session.
+      accept_confirm do
+        visit("about:blank")
+      end
     end
   end