Remove code duplication and improve style.

gclient_scm.py

 # Copyright (c) 2010 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.
 
 """Gclient-specific SCM-specific operations."""
 
 import logging
 import os
 import posixpath
 import re
@@ skipping 635 matching lines @@
         cwd = self.checkout_path
     stdout = None
     if redirect_stdout:
       stdout = subprocess.PIPE
     if cwd == None:
       cwd = self.checkout_path
     cmd = [scm.GIT.COMMAND]
     cmd.extend(args)
     logging.debug(cmd)
     try:
-      sp = subprocess.Popen(cmd, cwd=cwd, stdout=stdout)
+      sp = gclient_utils.Popen(cmd, cwd=cwd, stdout=stdout)
       output = sp.communicate()[0]
     except OSError:
       raise gclient_utils.Error("git command '%s' failed to run." %
               ' '.join(cmd) + "\nCheck that you have git installed.")
     if sp.returncode:
       raise gclient_utils.Error('git command %s returned %d' %
                                 (args[0], sp.returncode))
     if output is not None:
       return output.strip()
 
@@ skipping 294 matching lines @@
 
     This method returns a new list to be used as a command."""
     new_command = command[:]
     if revision:
       new_command.extend(['--revision', str(revision).strip()])
     # --force was added to 'svn update' in svn 1.5.
     if ((options.force or options.manually_grab_svn_rev) and
         scm.SVN.AssertVersion("1.5")[0]):
       new_command.append('--force')
     return new_command