In this particular location of fsck the index should have already
been opened by verify_pack, which is called just before we get
here and loop through the object names. However, just in case a
future version of that function does not use the index file we'll
double-check its open before we access the num_objects field.
Better safe now than sorry later.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>