For image with tree reloc tree, if its height is over level 2, the root
node's backref will point to itself. It's valid for kernel, but quota
verify code can't handle it and cause a infinite call, overflowing the
stack.
Add minimal image to reproduce the bug, as regression test.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ minor cleanups in test.sh ]
Signed-off-by: David Sterba <dsterba@suse.com>
