Fix formatting blockquote in verbatim

Reported at #907 (comment)

Author: nobu

lib/rdoc/markup/parser.rb

@@ -287,6 +287,8 @@ def build_verbatim margin
         line << ' ' * indent
       when :BREAK, :TEXT then
         line << data
+      when :BLOCKQUOTE then
+        line << '>>>'
       else # *LIST_TOKENS
         list_marker = case type
                       when :BULLET then data

test/rdoc/test_rdoc_markup_to_html.rb

@@ -812,6 +812,17 @@ def test_list_verbatim_2
     assert_equal expected, @m.convert(str, @to)
   end
 
+  def test_block_quote_in_verbatim
+    str = "BlockQuote\n  >>>\n"
+
+    expected = <<-EXPECTED
+<p>BlockQuote</p>
+<pre>&gt;&gt;&gt;</pre>
+    EXPECTED
+
+    assert_equal expected, @m.convert(str, @to).gsub(/^\n/, "")
+  end
+
   def test_parseable_eh
     valid_syntax = [
       'def x() end',