[FIX] Make redis pipelines always nonzero
[FIX] Make redis pipelines always nonzero

otherwise `if redis_write_client:` etc. fails if the pipeline is empty
which is very likely the case

indico/indico,mvidalgarcia/indico,mic4ael/indico,OmeGak/indico,DirkHoffmann/indico,pferreir/indico,DirkHoffmann/indico,ThiefMaster/indico,OmeGak/indico,mvidalgarcia/indico,DirkHoffmann/indico,mic4ael/indico,ThiefMaster/indico,mvidalgarcia/indico,mic4ael/indico,ThiefMaster/indico,DirkHoffmann/indico,pferreir/indico,indico/indico,pferreir/indico,pferreir/indico,indico/indico,OmeGak/indico,mic4ael/indico,indico/indico,mvidalgarcia/indico,ThiefMaster/indico,OmeGak/indico