Issue 51059 - If dbhome directory is set online backup fails
    
    Bug Description: If the dbhome directory is set, eg to /dev/shm/instance
    then an online backup fails because it looks for the log.000000x file
    in the wring diretcory.
    This is hidden because the return code is overwritten before checking.
    
    Fix Description: If dblayer_backup function fails - go to error processing
    section.
    
    https://pagure.io/389-ds-base/issue/51059
    
    Reviewed by: mreynolds (Thanks!)