Make QUIC_BAD_MULTIPATH_FLAG error log entry more informative.

net/quic/core/quic_connection.cc

Index: net/quic/core/quic_connection.cc
diff --git a/net/quic/core/quic_connection.cc b/net/quic/core/quic_connection.cc
index aba5db4d3e40dc77925cc1c8800710776ff8d8a5..8cff7e0762acd3f92f0ec693495c1718d0b38160 100644
--- a/net/quic/core/quic_connection.cc
+++ b/net/quic/core/quic_connection.cc
@@ -929,7 +929,7 @@ bool QuicConnection::OnConnectionCloseFrame(
            << ", with error: " << QuicUtils::ErrorToString(frame.error_code)
            << " (" << frame.error_details << ")";
   if (frame.error_code == QUIC_BAD_MULTIPATH_FLAG) {
-    LOG(ERROR) << " quic_version: " << version()
+    LOG(ERROR) << "Unexpected QUIC_BAD_MULTIPATH_FLAG error."
                << " last_received_header: " << last_header_
                << " encryption_level: " << encryption_level_;
   }