distgit/pagure: Set git directories as safe
    
    This was fixed previously for pagure.io in the context of
    paguremirroring. Turns out, it affects all kinds of git operations, so
    document and move accordingly.
    
    Fixes: releng#12181
    Fixes: fedora-infrastructure#12010
    
    Signed-off-by: Nils Philippsen <nils@redhat.com>