I am using Windows 7. After a "Save as..." of a file I noticed that the tab tooltip still shows the old path. I am not aware of any additional information being useful to this issue. If I left something out, drop me a message.
Maybe that I use vertical split view.
Could not reproduce on openSUSE Tumbleweed. Even with a split view, both tabs containing the file change their tooltip after Save As...
Works for me, too, with e.g. current master.