Use Bot in compare_failures

tools/gardening/lib/src/client.dart

Index: tools/gardening/lib/src/client.dart
diff --git a/tools/gardening/lib/src/client.dart b/tools/gardening/lib/src/client.dart
index 95424fb72ca195613d68b57589845c315abcad66..e60c872f3db8480e9fea903bb0e796a6a3b1c739 100644
--- a/tools/gardening/lib/src/client.dart
+++ b/tools/gardening/lib/src/client.dart
@@ -35,8 +35,7 @@ class HttpBuildbotClient implements BuildbotClient {
 
     void skipToPreviousBuildNumber() {
       BuildUri prevBuildUri = buildUri.prev();
-      log('Skip build number '
-          '${buildUri.buildNumber} -> ${prevBuildUri.buildNumber}');
+      log('Skip build number on ${buildUri} -> ${prevBuildUri.buildNumber}');
       buildUri = buildUri.prev();
     }