imply hiding_behind_another -> behind_another

BUR #13496 has been rejected.

create implication hiding_behind_another -> behind_another

A character hiding behind another is necessarily behind another.

behind another looks like either a critically underpopulated tag, or padding for people who didn't know about more specific tags. In theory it should imply several large tags like hug from behind, grabbing from behind and sex from behind.

This bulk update request is pending automatic rejection in 5 days.

This bulk update request has been rejected because it was not approved within 45 days.

The bulk update request #13496 (forum #226930) has been rejected by @DanbooruBot.