Log when 'cloudtail_utils.py stop' can't find cloudtail PID.

scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py

 #!/usr/bin/env python
 # Copyright (c) 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import errno
 import os
 import signal
 import subprocess
@@ skipping 47 matching lines @@
   """Send SIGINT to pid and wait termination of pid.
 
   Args:
     pid(int): pid of process which this function waits termination.
 
   Raises:
     OSError: is_running_posix, os.waitpid and os.kill may throw OSError.
     NotDiedError: if cloudtail is running after 10 seconds waiting,
                   NotDiedError is raised.
   """
+
   try:
     os.kill(pid, signal.SIGINT)
   except OSError as e:
     # Already dead?
     if e.errno in (errno.ECHILD, errno.EPERM, errno.ESRCH):
+      print('Can\'t send SIGINT to process %d. Already dead? Errno %d.' %
+            (pid, e.errno))
       return
     raise
 
   print('SIGINT has been sent to process %d. '
         'Going to wait for the process finishes.' % pid)
   if os.name == 'nt':
     try:
       os.waitpid(pid, 0)
     except OSError as e:
       if e.errno == errno.ECHILD:
@@ skipping 47 matching lines @@
       try:
         os.kill(pid, signal.SIGTERM)
       except OSError as e:
         print('Failed to send SIGTERM to process %d: %s' % (pid, e))
       # We do not reraise because I believe not suspending the process
       # is more important than completely killing cloudtail.
 
 
 if '__main__' == __name__:
   sys.exit(main())