should rescue Errno::EINVAL from TCPServer#accept. this exception
might occur if the server socket is not in ready to listen.
* lib/webrick/server.rb (WEBrick::GenericServer#accept_client):
don't call TCPServer#close if the :ShutdownSocketWithoutClose is set.
* lib/webrick/config.rb (WEBrick::Config::General): add new parameter
:ShutdownSocketWithoutClose.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14306 b2dd03c8-39d4-4d8f-98ff-823fe69b080e