I don't know about JDK-8073710 but for me the test fails apparently because some content of too big buffered images appeared different outside of a JLabel area.
A printout from the test reports that two JFrames have exactly the same dimensions:
frame0,200,200,200x90,layout=java.awt.BorderLayout,title=,resizable,normal,defaultCloseOperation=HIDE_ON_CLOSE,rootPane=javax.swing.JRootPane[,6,28,188x56 etc.

and the test fails at (0,56) -- as you can see 56 is the height of the rootPane.

I think the test should be someway changed since there's no point in researching why exactly these images are different: I even suspect there's nothing wrong with it -- the painting of the frame itself is not finished yet.