Add a nice message for cygwin users, telling them to rebase when necessary.

gclient_utils.py

 # Copyright 2009 Google Inc.  All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 55 matching lines @@
   logging.debug(u'%s, cwd=%s' % (u' '.join(args), kwargs.get('cwd', '')))
   if not 'env' in kwargs:
     # It's easier to parse the stdout if it is always in English.
     kwargs['env'] = os.environ.copy()
     kwargs['env']['LANGUAGE'] = 'en'
   if not 'shell' in kwargs:
     # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for the
     # executable, but shell=True makes subprocess on Linux fail when it's called
     # with a list because it only tries to execute the first item in the list.
     kwargs['shell'] = (sys.platform=='win32')
-  return subprocess.Popen(args, **kwargs)
+  try:
+    return subprocess.Popen(args, **kwargs)
+  except OSError, e:
+    if e.errno == errno.EAGAIN and sys.platform == 'cygwin':
+      raise Error(
+          'Visit '
+          'http://code.google.com/p/chromium/wiki/CygwinDllRemappingFailure to '
+          'learn how to fix this error; you need to rebase your cygwin dlls')
+    raise
 
 
 def CheckCall(command, cwd=None, print_error=True):
   """Similar subprocess.check_call() but redirects stdout and
   returns (stdout, stderr).
 
   Works on python 2.4
   """
   try:
     stderr = None
@@ skipping 552 matching lines @@
         logging.info('Caught exception in thread %s' % self.item.name)
         logging.info(str(sys.exc_info()))
         work_queue.exceptions.put(sys.exc_info())
       logging.info('Task %s done' % self.item.name)
 
       work_queue.ready_cond.acquire()
       try:
         work_queue.ready_cond.notifyAll()
       finally:
         work_queue.ready_cond.release()