Fix a presubmit.py breakage on python 2.4

Review URL: http://codereview.chromium.org/100220

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@15044 0039d316-1c4b-4281-b951-d872f2087c98

presubmit.py

@@ -630,7 +630,7 @@ def DoPresubmitChecks(change_info,
     if verbose:
       print "Running %s" % filename
     # Accept CRLF presubmit script.
-    presubmit_script = gcl.ReadFile(filename, 'Ur')
+    presubmit_script = gcl.ReadFile(filename, 'rU')
     results += executer.ExecPresubmitScript(presubmit_script, filename)
 
   errors = []