authentication_policy: check isPasswordValid on the login corresponding to that username

Useful in the context of password reset

bt5/erp5_authentication_policy/SkinTemplateItem/portal_skins/erp5_authentication_policy/Login_isPasswordValid.py

@@ -14,4 +14,11 @@ def doValidation(login, password):
     raise ValidationError('external_validator_failed', context, error_text=message)
   return 1
 
+user_login = request.get('field_user_login', None)
+# find login account provider and validate it on it (password recovered for an existing account)
+if user_login:
+  login = context.Base_getLoginValueByUserName(user_name)
+  if user is not None:
+    return doValidation(login, password)
+
 return doValidation(context, password)