make-jpkg doesn't work with the early access version because it doesn't
recognize the version from the name of the file. The format expected is:
jre-([0-9]+)u([0-9]+)-linux-(i586|x64|amd64)\.(bin|tar\.gz)
So you can work around this issue by renaming the file to
jre-8u0-linux-x64.tar.gz
Emmanuel Bourg