Environment

Redmine version: 3.4.2.stable
Ruby version: 2.3.0-p0
Rails version: 4.2.8
Database: pgsql 9.2

Example
Person A created an issue and has the page right after creation still opened. The issue has been assigned to person B.
Person B now edits the issue, adds some more details and submits the changes.
Person A, who still has the page opened after creating the issue, now wants to add some details to the issue which were not there.
Person A now clicks on the +Edit+-link, enters all the changes which are to be made and clicks on the +Submit+-button.
Person A is now shown the most useful information who made the changes, when they were made and which ones.

Desired behaviour
As person A clicks on the +Edit+-link an information that the issue has already been updated since it was last read should be displayed (preferably with a link to reload the issue (page) to read the entity from the database.