shill: connection: Flush routes when default connection changes

Also be more verbose with address configuration.

BUG=None
TEST=Unit tests

Change-Id: I7a419f416e6ed6b583d57a06b7be42ed37933593
Reviewed-on: https://gerrit.chromium.org/gerrit/24936
Commit-Ready: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/routing_table.cc b/routing_table.cc
index 818ed7f..1b3f6db 100644
--- a/routing_table.cc
+++ b/routing_table.cc
@@ -500,6 +500,9 @@
                                       int interface_index,
                                       int tag,
                                       const Query::Callback &callback) {
+  // Make sure we don't get a cached response that is no longer valid.
+  FlushCache();
+
   RTNLMessage message(
       RTNLMessage::kTypeRoute,
       RTNLMessage::kModeQuery,