drop skipped content inside a delimited block

- drop skipped content inside of creating empty paragraphs
- add missing test for scenario

lib/asciidoctor/parser.rb

@@ -444,13 +444,12 @@ def self.next_block(reader, parent, attributes = {}, options = {})
     if options.fetch :parse_metadata, true
       # read lines until there are no more metadata lines to read
       while parse_block_metadata_line reader, document, attributes, options
+        # discard the line just processed
         advanced = reader.advance
+        reader.skip_blank_lines
       end
-      if advanced && !reader.has_more_lines?
-        # NOTE there are no cases when these attributes are used, but clear them anyway
-        attributes.clear
-        return
-      end
+      # QUESTION should we clear the attributes?
+      return if advanced && !reader.has_more_lines?
     end
 
     if (extensions = document.extensions)
@@ -719,6 +718,7 @@ def self.next_block(reader, parent, attributes = {}, options = {})
         if in_list && lines.empty?
           # call advance since the reader preserved the last line
           reader.advance
+          # QUESTION should we clear attributes?
           return
         end
 

test/blocks_test.rb

@@ -85,6 +85,23 @@
       assert_xpath '//p', output, 2
     end
 
+    test 'comment block between paragraphs offset by blank lines inside delimited block' do
+      input = <<-EOS
+====
+first paragraph
+
+////
+block comment
+////
+
+second paragraph
+====
+      EOS
+      output = render_embedded_string input
+      refute_match(/block comment/, output)
+      assert_xpath '//p', output, 2
+    end
+
     test 'adjacent comment block between paragraphs' do
       input = <<-EOS
 first paragraph