• Project "Secret" contains users "Alice" and "Bob".
• The "Secret" project is added as a group reviewer on a diff.
• Alice selects "accept" from the actions dropdown, and leaves the default of accepting on behalf of herself and Secret; she does not yet hit "Submit."
• Simultaneously, Bob does the same thing, leaving both checkboxes selected, but not hitting "Submit."
• Alice then hits "Submit," which proceeds flawlessly.
• Bob hits Submit, and receives the message:

Ideally, this would be a silent no-op, not a message that might imply to Bob that he is no longer a member of the Secret group.