Adjust cherry-pick for Python2

Add InvalidFileException class.
RaisesRegex is RaisesRegexp in python2.
plistlib.loads is in the python3 version of plistlib,
but there are too many changes to backport this simply.

Lib/plistlib.py

@@ -479,3 +479,8 @@ def end_data(self):
         self.addObject(Data.fromBase64(self.getData()))
     def end_date(self):
         self.addObject(_dateFromString(self.getData()))
+
+
+class InvalidFileException (ValueError):
+    def __init__(self, message="Invalid file"):
+        ValueError.__init__(self, message)

Lib/test/test_plistlib.py

@@ -209,9 +209,9 @@ def test_nondictroot(self):
         self.assertEqual(test2, result2)
 
     def test_xml_plist_with_entity_decl(self):
-        with self.assertRaisesRegex(plistlib.InvalidFileException,
+        with self.assertRaisesRegexp(plistlib.InvalidFileException,
                                     "XML entity declarations are not supported"):
-            plistlib.loads(XML_PLIST_WITH_ENTITY, fmt=plistlib.FMT_XML)
+            plistlib.readPlistFromString(XML_PLIST_WITH_ENTITY)
 
 def test_main():
     test_support.run_unittest(TestPlistlib)