message: test: fix integration test flake.
  testEquivalent() was comparing two responses, both of which had a date: header with real time at
  second granularity. When this straddled a second boundary, the test would fail, resulting in flakey
  tests.
diff: #include <functional>
  #include <list>
  #include <memory>
  +#include <regex>
  #include <string>
  #include <vector>
  @@ -34,6 +35,14 @@ using testing::Invoke;
  using testing::_;
  namespace Envoy {
  +
  +namespace {
  +std::string normalizeDate(const std::string& s) {
  + const std::regex date_regex("date:[^\r]+");
  + return std::regex_replace(s, date_regex, "date: Mon, 01 Jan 2017 00:00:00 GMT");
  +}
  +} // namespace
  +
  IntegrationStreamDecoder::IntegrationStreamDecoder(Event::Dispatcher& dispatcher)
  : dispatcher_(dispatcher) {}
  @@ -993,7 +1002,7 @@ void BaseIntegrationTest::testEquivalent(const std::string& request) {
  connection2.run();
  - EXPECT_TRUE(response1 == response2);
  + EXPECT_EQ(normalizeDate(response1), normalizeDate(response2));
  }
  void BaseIntegrationTest::testBadPath() {
  