Update shell completion: generate-upgrade
Update shell completion: generate-upgrade

Add generate-upgrade and previous_release=.

csyangchen/rebar,project-fifo/rebar3,K2InformaticsGmbH/rebar,norton/rebar,apache/couchdb-rebar,rebar/rebar,evnix/rebar,heroku/rebar,blt/rebar3,sile/rebar3,surik/rebar3,benoitc/rebar3,vladdu/rebar3,wcy123/rebar,scatterbrain/rebar,platinumthinker/rebar,lrascao/rebar,norton/rebar,oubiwann/rebar,walrusVision/rebar3,thomasbhatia/rebar,fabiankrol/rebar3,thomasbhatia/rebar,macintux/rebar,jbalint/rebar3,kellymclaughlin/rebar3,processone/rebar3,beni55/rebar,fishcakez/rebar3,CMoH/rebar,jacktang/rebar,matwey/rebar,GabrielNicolasAvellaneda/rebar,lpgauth/rebar,blt/rebar3,deadok22/rebar,choptastic/rebar,syl20bnr/rebar,macintux/rebar,jacktang/rebar,choptastic/rebar,scatterbrain/rebar,macintux/rebar,bsmr-erlang/rebar,evnix/rebar,walrusVision/rebar3,shkumagai/rebar,fauxsoup/rebar3,linearregression/rebar3,oubiwann/rebar,matwey/rebar,deadok22/rebar,linearregression/rebar3,lpgauth/rebar,tsloughter/rebar3,GabrielNicolasAvellaneda/rebar,K2InformaticsGmbH/rebar,choptastic/rebar,SiDen/rebar,bsmr-erlang/rebar,evnix/rebar,lpgauth/rebar,SiDen/rebar,matwey/rebar,apache/couchdb-rebar,K2InformaticsGmbH/rebar,CMoH/rebar,project-fifo/rebar3,wcy123/rebar,rebar/rebar3,beni55/rebar,norton/rebar,lrascao/rebar3,syl20bnr/rebar,lrascao/rebar,zugolosian/rebar3,processone/rebar3,surik/rebar3,SiDen/rebar,thomasbhatia/rebar,zugolosian/rebar3,lrascao/rebar,jacktang/rebar,basho/rebar,basho/rebar,shkumagai/rebar,beni55/rebar-1,bsmr-erlang/rebar,apache/couchdb-rebar,rebar/rebar,heroku/rebar,csyangchen/rebar,platinumthinker/rebar,GabrielNicolasAvellaneda/rebar,beni55/rebar-1,djnym/rebar3,K2InformaticsGmbH/rebar,dcarastan/rebar,saleyn/rebar3,cloudant/couchdb-rebar,platinumthinker/rebar,norton/rebar3,csyangchen/rebar,erlang/rebar3,lrascao/rebar,syl20bnr/rebar,matwey/rebar,paulo-ferraz-oliveira/rebar,norton/rebar,matwey/rebar,paulo-ferraz-oliveira/rebar,scatterbrain/rebar,dcarastan/rebar,fabiankrol/rebar3,beni55/rebar,benoitc/rebar3,oubiwann/rebar,paulo-ferraz-oliveira/rebar,fauxsoup/rebar3,rebar/rebar,cloudant/couchdb-rebar,shkumagai/rebar,bsmr-erlang/rebar,ferd/rebar3,RubberCthulhu/rebar,rebar/rebar3,jbalint/rebar3,sile/rebar3,RubberCthulhu/rebar,cloudant/couchdb-rebar,CMoH/rebar,dcarastan/rebar,lrascao/rebar,K2InformaticsGmbH/rebar