Fix some path processing to work better on Windows.

R=hinoka@chromium.org
BUG=555036

Review URL: https://codereview.chromium.org/1471973004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@297698 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/gerrit_util.py b/gerrit_util.py
index bafd60a..38ac6aa 100755
--- a/gerrit_util.py
+++ b/gerrit_util.py
@@ -97,7 +97,7 @@
   @staticmethod
   def _get_netrc():
     path = '_netrc' if sys.platform.startswith('win') else '.netrc'
-    path = os.path.join(os.environ['HOME'], path)
+    path = os.path.expanduser(os.path.join('~', path))
     try:
       return netrc.netrc(path)
     except IOError: