Note that the IcedTea bug referred to above was actually the opposite (JPEG support broken for *non*-system-libjpeg builds. This bug involves a system-libjpeg build.
I had a quick look at the system-libjpeg.diff patch to the Debian package, and no problem jumped out at me. I can confirm that the workaround of copying libjavajpeg.so from JDK 7 into the JDK 8 directory works nicely. -- http://rrt.sc3d.org