rustup: Don't attempt to download SHA if it exists
rustup: Don't attempt to download SHA if it exists

This way installer can work fully in offline mode.

Put pre-downloaded files
(rust-nightly-x86_64-unknown-linux-gnu.tar.gz and
 rust-nightly-x86_64-unknown-linux-gnu.tar.gz.sha256)
into the $HOME/.rustup/YYYY-MM-DD directory
as it would be done by script itself.

Specify --save and --date=YYYY-MM-DD when running.
Files will be picked up and used to install in offline mode.

mvdnes/rust,ebfull/rust,avdi/rust,jroesch/rust,dinfuehr/rust,mdinger/rust,philyoon/rust,avdi/rust,ebfull/rust,miniupnp/rust,nwin/rust,jashank/rust,vhbit/rust,seanrivera/rust,AerialX/rust,ejjeong/rust,rohitjoshi/rust,philyoon/rust,zubron/rust,ejjeong/rust,robertg/rust,l0kod/rust,graydon/rust,aepsil0n/rust,KokaKiwi/rust,AerialX/rust-rt-minimal,sae-bom/rust,kwantam/rust,philyoon/rust,seanrivera/rust,sae-bom/rust,miniupnp/rust,dwillmer/rust,avdi/rust,AerialX/rust-rt-minimal,l0kod/rust,sae-bom/rust,victorvde/rust,KokaKiwi/rust,miniupnp/rust,miniupnp/rust,miniupnp/rust,richo/rust,nwin/rust,zachwick/rust,victorvde/rust,andars/rust,dinfuehr/rust,krzysz00/rust,AerialX/rust-rt-minimal,aneeshusa/rust,dwillmer/rust,zaeleus/rust,bombless/rust,rprichard/rust,ruud-v-a/rust,XMPPwocky/rust,KokaKiwi/rust,vhbit/rust,pshc/rust,kwantam/rust,krzysz00/rust,zubron/rust,hauleth/rust,jroesch/rust,cllns/rust,mdinger/rust,mdinger/rust,AerialX/rust,gifnksm/rust,dinfuehr/rust,pelmers/rust,pshc/rust,KokaKiwi/rust,richo/rust,carols10cents/rust,rohitjoshi/rust,aneeshusa/rust,jroesch/rust,AerialX/rust,zaeleus/rust,ruud-v-a/rust,nwin/rust,aneeshusa/rust,hauleth/rust,GBGamer/rust,robertg/rust,graydon/rust,bombless/rust,pshc/rust,mdinger/rust,graydon/rust,richo/rust,robertg/rust,miniupnp/rust,rprichard/rust,miniupnp/rust,ejjeong/rust,avdi/rust,untitaker/rust,nwin/rust,sae-bom/rust,KokaKiwi/rust,hauleth/rust,jashank/rust,GBGamer/rust,AerialX/rust-rt-minimal,mvdnes/rust,pshc/rust,mahkoh/rust,cllns/rust,krzysz00/rust,seanrivera/rust,carols10cents/rust,graydon/rust,untitaker/rust,nwin/rust,krzysz00/rust,nwin/rust,jashank/rust,aneeshusa/rust,ebfull/rust,aneeshusa/rust,andars/rust,dwillmer/rust,jashank/rust,l0kod/rust,nwin/rust,mvdnes/rust,reem/rust,TheNeikos/rust,aneeshusa/rust,gifnksm/rust,mvdnes/rust,andars/rust,victorvde/rust,dwillmer/rust,robertg/rust,cllns/rust,mihneadb/rust,graydon/rust,aidancully/rust,ruud-v-a/rust,dinfuehr/rust,vhbit/rust,aepsil0n/rust,hauleth/rust,reem/rust,bombless/rust,victorvde/rust,l0kod/rust,GBGamer/rust,rohitjoshi/rust,seanrivera/rust,pelmers/rust,l0kod/rust,mvdnes/rust,TheNeikos/rust,ejjeong/rust,GBGamer/rust,omasanori/rust,vhbit/rust,zachwick/rust,gifnksm/rust,TheNeikos/rust,richo/rust,seanrivera/rust,mihneadb/rust,dinfuehr/rust,avdi/rust,aepsil0n/rust,ruud-v-a/rust,hauleth/rust,untitaker/rust,ebfull/rust,untitaker/rust,rprichard/rust,andars/rust,aidancully/rust,victorvde/rust,reem/rust,mihneadb/rust,nwin/rust,AerialX/rust-rt-minimal,bombless/rust,jroesch/rust,GBGamer/rust,sae-bom/rust,dwillmer/rust,kwantam/rust,zubron/rust,richo/rust,victorvde/rust,avdi/rust,bombless/rust,ruud-v-a/rust,robertg/rust,jroesch/rust,mihneadb/rust,omasanori/rust,XMPPwocky/rust,l0kod/rust,AerialX/rust,philyoon/rust,ebfull/rust,gifnksm/rust,pelmers/rust,carols10cents/rust,cllns/rust,XMPPwocky/rust,zaeleus/rust,seanrivera/rust,aidancully/rust,pelmers/rust,pshc/rust,mdinger/rust,miniupnp/rust,omasanori/rust,zubron/rust,mahkoh/rust,dwillmer/rust,kwantam/rust,zaeleus/rust,mdinger/rust,AerialX/rust-rt-minimal,TheNeikos/rust,vhbit/rust,zachwick/rust,philyoon/rust,vhbit/rust,ejjeong/rust,aidancully/rust,AerialX/rust,carols10cents/rust,untitaker/rust,GBGamer/rust,mahkoh/rust,omasanori/rust,KokaKiwi/rust,sae-bom/rust,jashank/rust,ruud-v-a/rust,zubron/rust,gifnksm/rust,rohitjoshi/rust,jashank/rust,jroesch/rust,mahkoh/rust,krzysz00/rust,dwillmer/rust,mahkoh/rust,rprichard/rust,omasanori/rust,untitaker/rust,XMPPwocky/rust,graydon/rust,reem/rust,vhbit/rust,dwillmer/rust,XMPPwocky/rust,XMPPwocky/rust,kwantam/rust,pelmers/rust,bombless/rust,l0kod/rust,dinfuehr/rust,TheNeikos/rust,andars/rust,ebfull/rust,carols10cents/rust,zaeleus/rust,aepsil0n/rust,zubron/rust,carols10cents/rust,jroesch/rust,zaeleus/rust,gifnksm/rust,jroesch/rust,rprichard/rust,mihneadb/rust,zachwick/rust,reem/rust,pshc/rust,vhbit/rust,jashank/rust,rprichard/rust,zachwick/rust,pshc/rust,rohitjoshi/rust,GBGamer/rust,philyoon/rust,richo/rust,robertg/rust,rohitjoshi/rust,zubron/rust,jashank/rust,pelmers/rust,aepsil0n/rust,AerialX/rust,mvdnes/rust,zubron/rust,kwantam/rust,andars/rust,cllns/rust,omasanori/rust,aidancully/rust,hauleth/rust,TheNeikos/rust,cllns/rust,reem/rust,l0kod/rust,mahkoh/rust,krzysz00/rust,ejjeong/rust,mihneadb/rust,aidancully/rust,aepsil0n/rust,pshc/rust,GBGamer/rust,zachwick/rust