Make the sharding supervisor print what commands in runs in a shard

tools/sharding_supervisor/sharding_supervisor.py

Index: tools/sharding_supervisor/sharding_supervisor.py
diff --git a/tools/sharding_supervisor/sharding_supervisor.py b/tools/sharding_supervisor/sharding_supervisor.py
index 83f860ce0e1245b9f41e8659ef8b67ed62d5b8c4..9b973a00e32aea0068949f223b8813322805dd1b 100755
--- a/tools/sharding_supervisor/sharding_supervisor.py
+++ b/tools/sharding_supervisor/sharding_supervisor.py
@@ -182,6 +182,8 @@ def RunShard(test, total_shards, index, gtest_args, stdout, stderr):
   # Allows ui_tests to be run in parallel on the same machine
   env["CHROME_LOG_FILE"] = "chrome_log_%d" % index
 
+  sys.stderr.write('RUNNING: [%s]\n' % str(args));
+
   return subprocess.Popen(
       args, stdout=stdout,
       stderr=stderr,