OpenSSL::SSL::SSLSocket#connect randomly hangs
In a test like test/drb/ut_drb_drbssl.rb,
OpenSSL::SSL::SSLSocket#connect) sleeps in
rb_wait_for_single_fd and sometimes it's never waken up.
I think it's related to timer thread elimination in Ruby 2.6 and so I suspect this issue exists in Ruby 2.6.
Backtrace dump: http://ci.rvm.jp/results/trunk-asserts@silicon-docker/1888234