Merge branch 'rs/lock-correct-ref-during-delete'

When "update-ref -d --no-deref SYM" tried to delete a symbolic ref
SYM, it incorrectly locked the underlying reference pointed by SYM,
not the symbolic ref itself.

* rs/lock-correct-ref-during-delete:
  refs: lock symref that is to be deleted, not its target

diff --cc refs.c
Simple merge