bs-upload-kernel: Wipe kernel-obs-build before upload
    (JSC-SLE#5501, boo#1211226, bsc#1218184)
    
    The kernel upload takes long enough for packages to start building
    during the upload. If the project contains kernel-obs-build binary that
    crashes on boot builds fail as a result. Wipe kernel-obs-build before
    the upload. Handle the case when the package does not exist yet by
    ignoring the error.