Terminate created threads.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58341 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/net/smtp/test_smtp.rb

@@ -162,7 +162,7 @@ module Net
       servers = Socket.tcp_server_sockets("localhost", 0)
       begin
         sock = nil
-        Thread.start do
+        t = Thread.start do
           sock = accept(servers)
           sock.close
         end
@@ -176,6 +176,7 @@ module Net
       ensure
         sock.close if sock
         servers.each(&:close)
+        t.join
       end
     end
 

test/ruby/test_exception.rb

@@ -727,6 +727,8 @@ end.join
       end
     end
     assert_nil(e.cause)
+  ensure
+    y.join
   end
 
   def test_cause_thread_with_cause