Make do-rebase generate proper patches regardless of git config
    
    The do-rebase script generate patches with git-format-patch, but the pkg
    expects some non-default git configurations for the diffs and stats.
    
    So instead requiring developers to setup these config options, pass them
    to git-format-patch in do-rebase to generate the proper patches.
    
    Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>