Hi
There are so many plugins for WordPress and there are so many developers working on different sites. We already know that editing a plugin is not a good idea, but still sometime a developer have to edit the plugin according to the client's instructions and in some cases a developer edits a plugin and doesn't notify the client that this plugin is edited and the next developer working on that site OR the client updates that plugin and loses all the changes.
My idea is that every plugin has a variable $edited = false; by default and when any developer makes any kind of changes in any plugin he/she can just change the value of that variable to $edited = true. Changing the value to true will add a label with plugin in the WordPress admin dashboard that this plugin is edited so please don't update it and should only be handled/updated by someone who knows what he/she is doing and or can put back the edited code in the plugin.
The extended version of this idea is that we can also create a file in plugin something like 'editing-change-log' where developer can leave comments for other developer that which file/function he/she has edited so the next person can handle that thing when he/she updates the plugin.