plumbing: packfile, apply small object reading optimization also for delta objects
plumbing: packfile, apply small object reading optimization also for delta objects

Signed-off-by: Filip Navara <6a727111bdb9b50ab70531a810066e7fefd75a18@emclient.com>

mcuadros/go-git,src-d/go-git,go-git/go-git,go-git/go-git,mcuadros/go-git,src-d/go-git