Fix 2 recently introduced errors.

scm.py

 # Copyright (c) 2006-2009 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 os
 import re
 import subprocess
 import sys
@@ skipping 345 matching lines @@
     Args:
       file: The file to check
       property_name: The name of the SVN property, e.g. "svn:mime-type"
 
     Returns:
       The value of the property, which will be the empty string if the property
       is not set on the file.  If the file is not under version control, the
       empty string is also returned.
     """
     output = SVN.Run(["propget", property_name, file], None)
-    if (output.startswith("svn: ") and
+    if (output and
+        output.startswith("svn: ") and
         output.endswith("is not under version control")):
       return ""
     else:
       return output
 
   @staticmethod
   def DiffItem(filename):
     """Diff a single file"""
     # Use svn info output instead of os.path.isdir because the latter fails
     # when the file is deleted.
@@ skipping 29 matching lines @@
       filename = filename.replace('\\', '/')
       data = "Index: %s\n" % filename
       data += ("============================================================="
                "======\n")
       # Note: Should we use /dev/null instead?
       data += "--- %s\n" % filename
       data += "+++ %s\n" % filename
       data += "@@ -0,0 +1,%d @@\n" % nb_lines
       data += ''.join(file_content)
     return data