It is possible to delete topic with other user's posts without DELETE_OTHER_POSTS permission

Preconditions:

• Register User1 and User2, add them into groups User1 and User2 respectively.
• Create Branch
• Allow DELETE_OWN_POSTS permission in Branch for User1

Steps to reproduce:

1. User1 creates new topic in Branch
2. User2 creates post in this topic
3. User1 tries to delete topic

AR: User1 is able to delete topic with posts from other users
ER: Impossible to delete own topic if there are other user's posts