1) Choose a Windows7/8/10 node and mark it offline in its configuration page
2) then mark it online
3) Create a job attached to this node with the Windows command: notepad.exe
4) Start your job, check that Notepad is started (dont close).
5) Cancel the build of the job and see that Notepad is still open.

On the windows node, if you manually restart the agent, this fixes the "kill behavior".

the problem also happens for an accidental deconnection/reconnection (that how we notificed that, because randomly it seems that the ProcessTreeKiller did not work anymore and it seemed that it happened after networks issues between the server and the node)