In verify_pack, a caller-supplied verification function is called.
The function returns an int. If that return value is non-zero,
verify_pack should fail.
The only caller of verify_pack is in builtin/fsck.c, whose verify_fn
returns a meaningful error code (which was then ignored). Now, fsck
might return a different error code (with more detail). This would
happen in the unlikely event that a commit or tree that is a valid git
object but not a valid instance of its type gets into a pack.
Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Jeff King <peff@peff.net>