Add some diagnostics to understand what goes on.

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index ad7e9f49663d6b11bbd603b1e9dc6f65dbe75382..5fb6ca8222d9442d730cfb465538efab1b99a914 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -1506,6 +1506,7 @@ class TestUtils {
    * [base] directory if that [relativePath] does not already exist.
    */
   static Directory mkdirRecursive(Path base, Path relativePath) {
+    print("======= $base|relativePath|${relativePath.isAbsolute}|${relativePath.segments}");
     if (relativePath.isAbsolute) {
       base = new Path('/');
     }