Merge branch 'cc/replace-graft-peel-tags'

Merge branch 'cc/replace-graft-peel-tags'

When given a tag that points at a commit-ish, "git replace --graft"
failed to peel the tag before writing a replace ref, which did not
make sense because the old graft mechanism the feature wants to
mimick only allowed to replace one commit object with another.
This has been fixed.

* cc/replace-graft-peel-tags:
  replace: peel tag when passing a tag first to --graft
  replace: peel tag when passing a tag as parent to --graft
  t6050: redirect expected error output to a file
  t6050: use test_line_count instead of wc -l