auth-rhodecode: don't fail on bcrypt if user password is set to None.

Default to emptry string to not cause an exception.

rhodecode/authentication/plugins/auth_rhodecode.py

@@ -114,7 +114,7 b' class RhodeCodeAuthPlugin(RhodeCodeAuthP'
             crypto_backend = auth.crypto_backend()
             password_encoded = safe_str(password)
             password_match, new_hash = crypto_backend.hash_check_with_upgrade(
-                password_encoded, userobj.password)
+                password_encoded, userobj.password or '')
 
             if password_match and new_hash:
                 log.debug('user %s properly authenticated, but '

rhodecode/model/user.py

@@ -256,8 +256,9 b' class UserModel(BaseModel):'
             log_create_user, check_allowed_create_user)
 
         def _password_change(new_user, password):
+            old_password = new_user.password or ''
             # empty password
-            if not new_user.password:
+            if not old_password:
                 return False
 
             # password check is only needed for RhodeCode internal auth calls
@@ -269,7 +270,7 b' class UserModel(BaseModel):'
                 if new_user.password == password:
                     return False
 
-                password_match = check_password(password, new_user.password)
+                password_match = check_password(password, old_password)
                 if not password_match:
                     return True