If assignee is not subscriber can't change assigne and comment in one step


we have problem when assignee try reassign taks to author in one step with comment. If i will do it in two steps it wil be succed.

Reproduction Instructions

  1. Create task and assign it to someone who is not subscriber.
  2. Assignee try create comment and reasign it to Reporter.

Phabricator/Arcanist Version
Output from Config > Version Information or arc version.

Phabricator Version Information

Library Version Date Branchpoint
phabricator bc4f86d27996 Mon, Oct 19
arcanist 4b3baca999a4 Fri, Oct 16

Other Version Information

Binary Version Path
php 7.2.24 fpm-fcgi
diff 3.6 /bin/diff
git 2.18.4 /bin/git
hg Not Available
pygmentize 2.2.0 /bin/pygmentize
svn Not Available

I can’t reproduce this by following your reproduction steps exactly as written:

Hello, thanks for reply. Here is gif how i reproduce it. If you can’t reproduce it is there some settings that can affect this behavior?

Reproduction Instructions

  1. Someone else create task where is me as assignee but not as subscriber (like on gif)
  2. i try change assigne and reply with comment.
    Thats all.

Here is task settings:
it must be Visibility and Edit policy setted to Subscribers.

I replayed with better specification and gif that reproduce it. Could you help me or it is feature or bug?