Fix scoped_label? check for admin view

On admin labels page all labels are "generic" labels, so
label's subject (project/group) is not available here. When
checking if a label is scoped label we should first check if
subject method is available.

ee/app/models/ee/label.rb

@@ -7,7 +7,7 @@ module EE
     SCOPED_LABEL_PATTERN = /^.*::/.freeze
 
     def scoped_label?
-      SCOPED_LABEL_PATTERN.match?(name) && subject.feature_available?(:scoped_labels)
+      SCOPED_LABEL_PATTERN.match?(name) && respond_to?(:subject) && subject.feature_available?(:scoped_labels)
     end
 
     def scoped_label_key

ee/spec/models/ee/label_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Label do
+  describe '#scoped_label?' do
+    context 'with scoped_labels available' do
+      before do
+        stub_licensed_features(scoped_labels: true)
+      end
+
+      it 'returns false for unscoped labels' do
+        expect(build(:label, title: 'some name').scoped_label?).to be_falsey
+      end
+
+      it 'returns true for scoped labels' do
+        expect(build(:label, title: 'key::some name').scoped_label?).to be_truthy
+      end
+
+      it 'returns false for scoped labels without subject' do
+        label = described_class.new(title: 'key::some name')
+
+        expect(label.scoped_label?).to be_falsey
+      end
+    end
+
+    context 'with scoped_labels not available' do
+      before do
+        stub_licensed_features(scoped_labels: false)
+      end
+
+      it 'returns false for scoped labels' do
+        expect(build(:label, title: 'key::some name').scoped_label?).to be_falsey
+      end
+    end
+  end
+
+  describe '#scoped_label_key' do
+    it 'returns key for scoped labels' do
+      mappings = {
+        'key1::key 2::some value' => 'key1::key 2::',
+        'key1::some value' => 'key1::',
+        '::some value' => '::',
+        'some value' => nil
+      }
+
+      mappings.each do |title, expected_key|
+        expect(build(:label, title: title).scoped_label_key).to eq(expected_key)
+      end
+    end
+  end
+end