There have been a series of failures of net_unittests on Mac:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.10%20Tests

It appears that local_test_server_posix.cc is failing to start. As the various failing tests show similar errors:

[ RUN      ] OCSPVerify/HTTPSOCSPVerifyTest.VerifyResult/2
[34975:779:0503/035159.275460:18520959759828:ERROR:local_test_server_posix.cc(81)] poll() timed out; bytes_read=0
[34975:779:0503/035159.275570:18520959847881:ERROR:local_test_server_posix.cc(169)] Could not read server_data_len
../../net/url_request/url_request_unittest.cc:10809: Failure
Value of: test_server.Start()
  Actual: false
Expected: true
Stack trace:
0   net_unittests                       0x000000010766f16b testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop(int) + 91
1   net_unittests                       0x000000010766eb29 testing::internal::AssertHelper::operator=(testing::Message const&) const + 89
2   net_unittests                       0x0000000107340c8b net::HTTPSOCSPTest::DoConnectionWithDelegate(net::BaseTestServer::SSLOptions const&, net::TestDelegate*, net::SSLInfo*) + 507
3   net_unittests                       0x0000000107340487 net::HTTPSOCSPVerifyTest_VerifyResult_Test::TestBody() + 359
../../net/url_request/url_request_unittest.cc:11668: Failure
Expected: DoConnectionWithDelegate(ssl_options, &delegate, &ssl_info) doesn't generate new fatal failures in the current thread.
  Actual: it does.
Stack trace:
0   net_unittests                       0x000000010766f16b testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop(int) + 91
1   net_unittests                       0x000000010766eb29 testing::internal::AssertHelper::operator=(testing::Message const&) const + 89
2   net_unittests                       0x00000001073404e2 net::HTTPSOCSPVerifyTest_VerifyResult_Test::TestBody() + 450
[  FAILED  ] OCSPVerify/HTTPSOCSPVerifyTest.VerifyResult/2,

Could someone on the net-dev team help triage this failure?