newgrounds: exclude links to other works in commentary.

Sometimes when a Newgrounds post is part of a set, there is a list of
links to other posts in the set in the artist's commentary. Exclude
these links because they're not really part of the commentary.

Example: https://www.newgrounds.com/art/view/boxofwant/annie-hughes-1 (NSFW)

app/logical/source/extractor/newgrounds.rb

@@ -68,11 +68,12 @@ module Source
       end
 
       def artist_commentary_desc
-        page&.css("#author_comments")&.to_html
+        return "" if page.nil?
+        page.dup.css("#author_comments").tap { _1.css("ul.itemlist").remove }.to_html
       end
 
       def dtext_artist_commentary_desc
-        DText.from_html(artist_commentary_desc)
+        DText.from_html(artist_commentary_desc).strip
       end
 
       def user_name

test/unit/sources/newgrounds_test.rb

@@ -98,6 +98,21 @@ module Sources
       end
     end
 
+    context "A post with links to other illustrations in the commentary" do
+      should "not include the links in the commentary" do
+        @source = Source::Extractor.find("https://www.newgrounds.com/art/view/boxofwant/annie-hughes-1")
+
+        assert_equal(<<~EOS.chomp, @source.artist_commentary_desc)
+          <div class="padded-top  ql-body " id="author_comments"><p>Commission of Annie Hughes, the mom from The Iron Giant, for <a href="https://twitter.com/ManStawberry" target="_blank" rel="noopener noreferrer nofollow">@ManStawberry</a>.</p><p><br></p>
+          </div>
+        EOS
+
+        assert_equal(<<~EOS.chomp, @source.dtext_artist_commentary_desc)
+          Commission of Annie Hughes, the mom from The Iron Giant, for "@ManStawberry":[https://twitter.com/ManStawberry].
+        EOS
+      end
+    end
+
     context "generating page urls" do
       should "work" do
         assert_equal("https://www.newgrounds.com/art/view/natthelich/fire-emblem-marth-plus-progress-pic", Source::URL.page_url("https://art.ngfiles.com/images/1033000/1033622_natthelich_fire-emblem-marth-plus-progress-pic.png?f1569487181"))