When I save a file, I expect the buffer's name to change to the file's name, not stay "Untitled-4". This used to be the case. In 5.1.0, it no longer works.
(NOTE: In screenshotting this but I noticed that the window title and the buffer tab names are DISJOINT, filing bug against core because the window title name is the one that's wrong!)
Can you reproduce this without plugins? jedit -noplugins is one way to try it.
Please attach an activity log that shows what happens, and also let me know if you can reproduce this without plugins.
Sorry - updated all plugins and the issue is gone.