Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2, -o help TEST_DIR/t.qcow2 128M
qemu-img: Invalid option list: backing_file=TEST_DIR/t.qcow2,
Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2, -o help TEST_DIR/t.qcow2 128M
qemu-img: Invalid option list: backing_file=TEST_DIR/t.qcow2,