message: build: updating stale comment
  Risk Level: n/a
  Testing: n/a
  Docs Changes: n/a
  Release Notes: n/a
diff: @@ -13,8 +13,9 @@ export ENVOY_SRCDIR="$(pwd)"
  # hard code this (basically due to how docker works).
  export NUM_CPUS=8
  -# Circle does not currently support IPv6 so we don't test it here. We will add and remove Travis
  -# when it is supported.
  +# CircleCI doesn't support IPv6 by default, so we run all tests with IPv4, and
  +# a limited subset with IPv6 using "machine: true" and do_circle_ci_ipv6_tests.sh
  +# (see https://circleci.com/docs/2.0/executor-types/#using-machine)
  export BAZEL_EXTRA_TEST_OPTIONS="--test_env=ENVOY_IP_TEST_VERSIONS=v4only"
  function finish {
  