Remove SENSIBLE_STACK_TRACES feature

nanoc/lib/nanoc/base/feature.rb

@@ -92,4 +92,3 @@ def self.all_outdated
 end
 
 Nanoc::Feature.define('live_cmd', version: '4.8')
-Nanoc::Feature.define('sensible_stack_traces', version: '4.8')

nanoc/lib/nanoc/cli/error_handler.rb

@@ -150,10 +150,7 @@ def write_verbose_error(error, stream)
 
     # @api private
     def forwards_stack_trace?
-      feature_enabled = Nanoc::Feature.enabled?(Nanoc::Feature::SENSIBLE_STACK_TRACES)
-      ruby_2_5_used = ruby_version.start_with?('2.5')
-
-      feature_enabled || ruby_2_5_used
+      ruby_version.start_with?('2.5')
     end
 
     # @api private

nanoc/spec/nanoc/cli/error_handler_spec.rb

@@ -6,38 +6,20 @@
   describe '#forwards_stack_trace?' do
     subject { error_handler.forwards_stack_trace? }
 
-    context 'feature enabled' do
-      around do |ex|
-        Nanoc::Feature.enable(Nanoc::Feature::SENSIBLE_STACK_TRACES) do
-          ex.run
-        end
-      end
-
-      context 'Ruby 2.4' do
-        it { is_expected.to be(true) }
+    context 'Ruby 2.4' do
+      before do
+        expect(error_handler).to receive(:ruby_version).and_return('2.4.2')
       end
 
-      context 'Ruby 2.5' do
-        it { is_expected.to be(true) }
-      end
+      it { is_expected.to be(false) }
     end
 
-    context 'feature not enabled' do
-      context 'Ruby 2.4' do
-        before do
-          expect(error_handler).to receive(:ruby_version).and_return('2.4.2')
-        end
-
-        it { is_expected.to be(false) }
+    context 'Ruby 2.5' do
+      before do
+        expect(error_handler).to receive(:ruby_version).and_return('2.5.0')
       end
 
-      context 'Ruby 2.5' do
-        before do
-          expect(error_handler).to receive(:ruby_version).and_return('2.5.0')
-        end
-
-        it { is_expected.to be(true) }
-      end
+      it { is_expected.to be(true) }
     end
   end