cmd/gb-vendor: remove partial copy on error
cmd/gb-vendor: remove partial copy on error

URXtech/gb,mopemope/gb,inconshreveable/gb,tbruyelle/gb,tianon/gb,Luit/gb,mopemope/gb,mopemope/gb,hyper-carrot/gb,guiquanz/gb,tianon/gb,constabulary/gb,lparkes/gb,tbruyelle/gb,constabulary/gb,ches/gb,constabulary/gb,MerlinDMC/gb,acasajus/gb,hyper-carrot/gb,davidkaya/gb,inconshreveable/gb,ches/gb,davidkaya/gb