Ignore output_dir when checking for excludes in pruner

nanoc/lib/nanoc/base/services/pruner.rb

@@ -43,10 +43,18 @@ def exclude?(component)
     #
     # @return [Boolean] true if the given file is excluded, false otherwise
     def filename_excluded?(filename)
-      pathname = Pathname.new(filename)
+      pathname = Pathname.new(strip_output_dir(filename))
       @exclude.any? { |e| pathname_components(pathname).include?(e) }
     end
 
+    def strip_output_dir(filename)
+      if filename.start_with?(@config[:output_dir])
+        filename[@config[:output_dir].size..-1]
+      else
+        filename
+      end
+    end
+
     def pathname_components(pathname)
       components = []
       tmp = pathname

nanoc/spec/nanoc/base/services/pruner_spec.rb

@@ -3,7 +3,7 @@
 describe Nanoc::Pruner do
   subject(:pruner) { described_class.new(config, reps, dry_run: dry_run, exclude: exclude) }
 
-  let(:config) { Nanoc::Int::Configuration.new({}) }
+  let(:config) { Nanoc::Int::Configuration.new({}).with_defaults }
   let(:dry_run) { false }
   let(:exclude) { [] }
 
@@ -25,6 +25,31 @@
     expect(Nanoc::Extra::Pruner).to equal(Nanoc::Pruner)
   end
 
+  describe '#filename_excluded?' do
+    subject { pruner.filename_excluded?(filename) }
+
+    let(:filename) { 'output/foo/bar.html' }
+
+    context 'nothing excluded' do
+      it { is_expected.to be(false) }
+    end
+
+    context 'matching identifier component excluded' do
+      let(:exclude) { ['foo'] }
+      it { is_expected.to be(true) }
+    end
+
+    context 'non-matching identifier component excluded' do
+      let(:exclude) { ['xyz'] }
+      it { is_expected.to be(false) }
+    end
+
+    context 'output dir excluded' do
+      let(:exclude) { ['output'] }
+      it { is_expected.to be(false) }
+    end
+  end
+
   describe '#pathname_components' do
     subject { pruner.pathname_components(pathname) }