Fix comparison of password types.

session.flush() on models with password type with the coercion
listener active raised a TypeError before.

sqlalchemy_utils/types/password.py

@@ -23,6 +23,11 @@ class Password(object):
             self.context = weakref.proxy(context)
 
     def __eq__(self, value):
+        if isinstance(value, Password):
+            # Comparing 2 hashes isn't very useful; but this equality
+            # method breaks otherwise.
+            return value.hash == self.hash
+
         valid, new = self.context.verify_and_update(value, self.hash)
         if valid and new:
             # New hash was calculated due to various reasons; stored one

tests/types/test_password.py

@@ -88,3 +88,15 @@ class TestPasswordType(TestCase):
 
     def test_without_schemes(self):
         assert PasswordType(schemes=[]).length == 1024
+
+    def test_compare(self):
+        from passlib.hash import md5_crypt
+
+        obj = self.User()
+        obj.password = Password(md5_crypt.encrypt('b'))
+
+        other = self.User()
+        other.password = Password(md5_crypt.encrypt('b'))
+
+        # Not sure what to assert here; the test raised an error before.
+        assert obj.password != other.password