Fix some path processing to work better on Windows.

scm.py

 # 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.
 
 """SCM-specific utility classes."""
 
 import cStringIO
 import glob
 import logging
 import os
@@ skipping 1022 matching lines @@
     else:
       regexp = re.compile(r'<%s:\d+> %s' % (realm, uuid))
     if regexp is None:
       return None
     if sys.platform.startswith('win'):
       if not 'APPDATA' in os.environ:
         return None
       auth_dir = os.path.join(os.environ['APPDATA'], 'Subversion', 'auth',
                               'svn.simple')
     else:
-      if not 'HOME' in os.environ:
+      auth_dir = os.path.expanduser(
+          os.path.join('~', '.subversion', 'auth', 'svn.simple'))
+      if not os.path.exists(auth_dir):
         return None
-      auth_dir = os.path.join(os.environ['HOME'], '.subversion', 'auth',
-                              'svn.simple')
     for credfile in os.listdir(auth_dir):
       cred_info = SVN.ReadSimpleAuth(os.path.join(auth_dir, credfile))
       if regexp.match(cred_info.get('svn:realmstring')):
         return cred_info.get('username')
 
   @staticmethod
   def ReadSimpleAuth(filename):
     f = open(filename, 'r')
     values = {}
     def ReadOneItem(item_type):
@@ skipping 113 matching lines @@
         # revert, like for properties.
         if not os.path.isdir(cwd):
           # '.' was deleted. It's not worth continuing.
           return
         try:
           SVN.Capture(['revert', file_status[1]], cwd=cwd)
         except subprocess2.CalledProcessError:
           if not os.path.exists(file_path):
             continue
           raise