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

e.g. http://build.chromium.org/p/chromium/builders/Linux%20Tests%20x64/builds/24938/steps/browser_tests/logs/stdio lacks some output at the end, and I'd like to know which tests are supposed to be there

BUG=none
TEST=none


Review URL: https://chromiumcodereview.appspot.com/10843027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149816 0039d316-1c4b-4281-b951-d872f2087c98

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,