Don't treat panics as failed installation
    
    If the new kernel is successfully installed, the machine tries to boot
    it. It sometimes happens that a kernel panic is encountered during the
    boot, which is still part of the kpkginstall task. Detect this as a
    kernel problem, not infrastructure error.
    
    Signed-off-by: Veronika Kabatova <vkabatov@redhat.com>