Let landmines print something when run as part of `gclient sync`.

build/landmines.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """
 This script runs every build as the first hook (See DEPS). If it detects that
 the build should be clobbered, it will delete the contents of the build
 directory.
 
@@ skipping 55 matching lines @@
   if os.path.exists(landmines_path):
     with open(landmines_path, 'r') as f:
       old_landmines = f.readlines()
     if old_landmines != new_landmines:
       old_date = time.ctime(os.stat(landmines_path).st_ctime)
       diff = difflib.unified_diff(old_landmines, new_landmines,
           fromfile='old_landmines', tofile='new_landmines',
           fromfiledate=old_date, tofiledate=time.ctime(), n=0)
       sys.stdout.write('Clobbering due to:\n')
       sys.stdout.writelines(diff)
+      sys.stdout.flush()
 
       clobber.clobber(out_dir)
 
   # Save current set of landmines for next time.
   with open(landmines_path, 'w') as f:
     f.writelines(new_landmines)
 
 
 def process_options():
   """Returns an options object containing the configuration for this script."""
@@ skipping 52 matching lines @@
     proc = subprocess.Popen([sys.executable, s], stdout=subprocess.PIPE)
     output, _ = proc.communicate()
     landmines.extend([('%s\n' % l.strip()) for l in output.splitlines()])
   clobber_if_necessary(landmines, options.src_dir)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())