Patrick Steinhardt [off-list ref] writes:

Changes in v8:
  - Pass `RESOLVE_REF_READING` to make `refs_resolve_ref_unsafe()`
    return a NULL pointer when it cannot resolve the reference.

OK.

  - Drop unneeded code that sets `head_target = "HEAD"` on detached
    HEAD.

OK.

  - Add a test case that verifies that we can drop commits with
    "--update-refs=head" and a detached HEAD.

OK.

Sounds good.  Will replace.
Thanks.