Steps to reproduce:
1. Install Email-ext plugin;
2. Create default multi-configuration project;
3. Select several nodes to run the job in multi-configuration project;
4. Add post-build action -> Editable Email Notification;
5. Set 'Trigger for matrix projects' = Trigger only the parent job -> Apply changes;
6. Reopen job configuration and observe the value of 'Trigger for matrix projects' property.