If the next steps happen:
1. User takes off manually a node with a reason "X"
2. The node connection to jenkins is broken. offline reason changes to ChannelTerminated
3. The user change something in the node configuration. (which make the offline reason move to the node and be persistent)
4. The node connection is restored. Offline reason stays ChannelTerminated.

This is in setNode function on Computer model which need to check if the node already have an offline reason and don't override it. (which is quite a problem since Node offlinecause is private...)