panic: runtime error: invalid memory address or nil pointer dereference
[signal sys: trap: fault read code=0x0 addr=0x0 pc=0x509499]

goroutine 1 [running]:
gopkg.in/src-d/go-git%2ev4.(*Worktree).doUpdateFileToIndex(0x4209a1a80, 0x420a18000, 0x5c3607, 0x9, 0x57122b07e48cd056, 0x74627f29f4985cc2, 0x3142bd393142bd39, 0x0, 0x420cd6200)
	/usr/henesy/git/src/gopkg.in/src-d/go-git.v4/worktree_status.go:375 +0x149
gopkg.in/src-d/go-git%2ev4.(*Worktree).addOrUpdateFileToIndex(0x4209a1a80, 0x5c3607, 0x9, 0x57122b07e48cd056, 0x74627f29f4985cc2, 0x3142bd39, 0x0, 0x0)
	/usr/henesy/git/src/gopkg.in/src-d/go-git.v4/worktree_status.go:343 +0x15e
gopkg.in/src-d/go-git%2ev4.(*Worktree).Add(0x4209a1a80, 0x5c3607, 0x9, 0x0, 0x0, 0x0, 0x18, 0x4208f3120)
	/usr/henesy/git/src/gopkg.in/src-d/go-git.v4/worktree_status.go:265 +0x2d1
main.main()
	/usr/henesy/prg/go/git/commit.go:35 +0x12c