Handle EOF from ReadAt in content.ReadBlob
Handle EOF from ReadAt in content.ReadBlob

Signed-off-by: Edgar Lee <a646603314b79f7746d0496839a2b53e37ac4430@netflix.com>

mikebrow/containerd,containerd/containerd,thaJeztah/containerd,dmcgowan/containerd,vdemeester/containerd,vdemeester/containerd,mikebrow/containerd,crosbymichael/containerd,estesp/containerd,thaJeztah/containerd,containerd/containerd,dmcgowan/containerd,crosbymichael/containerd,estesp/containerd