Confirmation message when discarding multiple users' changes in Channel Manager only displays the name of the first user

To reproduce:

• With editor1, make changes to a channel
• With editor2, make changes to the same channel
• With admin, choose to discard both changes in the channel
  Expected: All the usernames of the users with changes that will be discarded
  Actual: The message states: "Are you sure you want to discard all changes of editor1 ?"

See screenshot.

All selected changes are discarded.
This works fine for publishing.