Another RDoc choke on stdlib

Hi Dave,

Here’s another crash scenario. (Top-snipped)

                     cgi-lib.rb: c............
                     session.rb: cc........c......c.....
                   benchmark.rb: m......c..c..c...........
                      base64.rb: ....

Generating HTML…
/usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:372:in build_method_detail_list ': undefined methodas_href’ for nil (NameError)
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:368:in map' from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:368:ineach’
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:368:in map' from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:368:inbuild_method_detail_list’
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:357:in each' from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:357:inbuild_method_detail_list’
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:355:in each' from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:355:inbuild_method_detail_list’
… 9 levels…
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:1053:in generate_html' from /usr/local/lib/ruby/site_ruby/1.6/rdoc/generators/html_generator.rb:979:ingenerate’
from /usr/local/lib/ruby/site_ruby/1.6/rdoc/rdoc.rb:210:in `document’
from /usr/local/bin/rdoc:6