[DRE-maint] Bug#995815: ruby-eventmachine FTBFS on IPV6-only buildds

[Adrian Bunk]

Source: ruby-eventmachine
Version: 1.3~pre20190820-g10fb0c4-3
Severity: serious
Tags: ftbfs

https://buildd.debian.org/status/logs.php?pkg=ruby-eventmachine&arch=amd64

...
TestResolver:
  test_garbage:						F
===============================================================================
Failure: test_garbage(TestResolver)
/<<PKGBUILDDIR>>/tests/test_resolver.rb:58:in `test_garbage'
     55:   end
     56:
     57:   def test_garbage
  => 58:     assert_raises( ArgumentError ) {
     59:       EM.run {
     60:         EM::DNS::Resolver.resolve 123
     61:       }

<ArgumentError> expected but was
<RuntimeError(<no datagram socket>)
...
Finished in 8.026344954 seconds.
-------------------------------------------------------------------------------
274 tests, 3490 assertions, 2 failures, 24 errors, 0 pendings, 10 omissions, 0 notifications
90.1515% passed
-------------------------------------------------------------------------------
34.14 tests/s, 434.82 assertions/s
rake aborted!
Command failed with status (1): [ruby -w -I"tests" /usr/share/rubygems-integration/all/gems/rake-13.0.3/lib/rake/rake_test_loader.rb "tests/jruby/test_jeventmachine.rb" "tests/test_attach.rb" "tests/test_basic.rb" "tests/test_channel.rb" "tests/test_completion.rb" "tests/test_connection_count.rb" "tests/test_connection_write.rb" "tests/test_defer.rb" "tests/test_deferrable.rb" "tests/test_epoll.rb" "tests/test_error_handler.rb" "tests/test_exc.rb" "tests/test_file_watch.rb" "tests/test_fork.rb" "tests/test_futures.rb" "tests/test_handler_check.rb" "tests/test_hc.rb" "tests/test_httpclient.rb" "tests/test_httpclient2.rb" "tests/test_inactivity_timeout.rb" "tests/test_io_streamer.rb" "tests/test_ipv4.rb" "tests/test_ipv6.rb" "tests/test_iterator.rb" "tests/test_kb.rb" "tests/test_keepalive.rb" "tests/test_line_protocol.rb" "tests/test_ltp.rb" "tests/test_ltp2.rb" "tests/test_many_fds.rb" "tests/test_next_tick.rb" "tests/test_object_protocol.rb" "tests/test_pause.rb" "tests/test_pending_connect_timeout.rb" "tests/test_pool.rb" "tests/test_process_watch.rb" "tests/test_processes.rb" "tests/test_proxy_connection.rb" "tests/test_pure.rb" "tests/test_queue.rb" "tests/test_resolver.rb" "tests/test_running.rb" "tests/test_sasl.rb" "tests/test_send_file.rb" "tests/test_servers.rb" "tests/test_shutdown_hooks.rb" "tests/test_smtpclient.rb" "tests/test_smtpserver.rb" "tests/test_sock_opt.rb" "tests/test_spawn.rb" "tests/test_ssl_args.rb" "tests/test_ssl_dhparam.rb" "tests/test_ssl_ecdh_curve.rb" "tests/test_ssl_extensions.rb" "tests/test_ssl_methods.rb" "tests/test_ssl_protocols.rb" "tests/test_ssl_verify.rb" "tests/test_stomp.rb" "tests/test_system.rb" "tests/test_threaded_resource.rb" "tests/test_tick_loop.rb" "tests/test_timers.rb" "tests/test_ud.rb" "tests/test_unbind_reason.rb" -v]
/usr/share/rubygems-integration/all/gems/rake-13.0.3/exe/rake:27:in `<top (required)>'
Tasks: TOP => default
(See full trace by running task with --trace)
ERROR: Test "ruby2.7" failed. Exiting.
dh_auto_install: error: dh_ruby --install /<<BUILDDIR>>/ruby-eventmachine-1.3\~pre20201020-b50c135/debian/ruby-eventmachine returned exit code 1
make[1]: *** [debian/rules:13: override_dh_auto_install] Error 25