Organize: almost always "another member edited"

It appears that one gets very often the message:

organize.error.concurrency_text=While you were organizing this resource, another member changed its contents. In order to manage resource versions, your changes have been discarded. Please try again.

Even though one is alone at editing the resources.

This message is shown when revision numbers fetched at display time and just before save time differ.

My test got it to work the first time but failed the second.
One should:

• reproduce on current
• debug and find the cause, or, if unreproducible, enrich the message so that details about the concurrent change is given
• avoid it more often