docker/docker-registry — pull request #577 by ncdc (2014-09-17 17:19:41+00:00)
Title: Add image_id to tag_deleted signal payload

Add image_id to tag_deleted signal payload. This is useful for things
such as a refcount extension, which needs to know the image id that was
associated with the deleted tag so refcounts can be updated accordingly.

Extracted from the refcount PR #409 in preparation for making it a standalone extension via #566

@wking @dmp42 please review when you get a chance