Fix a python 2.6ism

Review URL: http://codereview.chromium.org/1627010

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@43960 0039d316-1c4b-4281-b951-d872f2087c98

gclient.py

@@ -403,7 +403,7 @@ class GClient(object):
     # makes testing a bit too fun.
     result = pprint.pformat(entries, 2)
     if result.startswith('{\''):
-      result[0:2] = '{ \''
+      result = '{ \'' + result[2:]
     text = "entries = \\\n" + result + '\n'
     file_path = os.path.join(self._root_dir, self._options.entries_filename)
     gclient_utils.FileWrite(file_path, text)