Finish threads.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46295 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rinda/test_rinda.rb

@@ -674,6 +674,7 @@ class TestRingServer < Test::Unit::TestCase
     skip 'IPv6 not available' unless
       Socket.ip_address_list.any? { |addrinfo| addrinfo.ipv6? }
 
+    @rs.shutdown
     begin
       @rs = Rinda::RingServer.new(@ts, [['ff02::1', '::1', 0]], @port)
     rescue Errno::EADDRNOTAVAIL