Fix 2 recently introduced errors.

TEST=none
BUG=none

Review URL: http://codereview.chromium.org/391072

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@32058 0039d316-1c4b-4281-b951-d872f2087c98

scm.py

@@ -363,7 +363,8 @@ class SVN(object):
       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:

trychange.py

@@ -151,7 +151,7 @@ class SVN(SCM):
       os.chdir(root)
 
     # Directories will return None so filter them out.
-    diff = filter(None, [scm.SVN.Diff(f) for f in files])
+    diff = filter(None, [scm.SVN.DiffItem(f) for f in files])
     os.chdir(previous_cwd)
     return "".join(diff)