Merge branch 'jk/nested-points-at'

"git tag --list --points-at X" showed tags that directly refers to
object X, but did not list a tag that points at such a tag, which
has been corrected.

* jk/nested-points-at:
  ref-filter: simplify return type of match_points_at
  ref-filter: avoid parsing non-tags in match_points_at()
  ref-filter: avoid parsing tagged objects in match_points_at()
  ref-filter: handle nested tags in --points-at option

diff --cc ref-filter.c
Simple merge