git/writer: remove support for w.Write(nil)
git/writer: remove support for w.Write(nil)

bozaro/git-lfs,Jericho25/-git-lfs_miilkyway,aleb/git-lfs,github/git-lfs,github/git-lfs,bozaro/git-lfs,aleb/git-lfs,aleb/git-lfs,Jericho25/-git-lfs_miilkyway,github/git-lfs,andyneff/git-lfs,andyneff/git-lfs,bozaro/git-lfs,dakotahawkins/git-lfs,andyneff/git-lfs,Jericho25/-git-lfs_miilkyway,dakotahawkins/git-lfs,dakotahawkins/git-lfs