"Prompt for checkout on asset modification" check box no longer makes "Files need checkout!" message appear

"Files need check-out!" dialog no longer appears when you begin to modify an asset that is not checked out.

Setting is enabled by default:

[Image Removed]

But message doesn't appear if you, for example, open a blueprint that is not checked out and add a new node to the graph.

This seems to be because in the UUnrealEdEngine::OnSourceControlStateUpdated function it skips displaying the notification if IsCookingInEditor() is true, and it seems like IsCookingInEditor() always returns true.

Might be the same root cause as [Link Removed], but the symptom is slightly different, so adding a separate bug just in-case