Posts: When using `wp_update_post()` on a `attachment` post_type item, pass...

Posts: When using `wp_update_post()` on a `attachment` post_type item, pass the `$wp_error` parameter through to `wp_insert_attachment()`.

Props MyThemeShop.
Fixes #41513.

Built from https://develop.svn.wordpress.org/trunk@42383


git-svn-id: https://core.svn.wordpress.org/trunk@42212 1a063a9b-81f0-0310-95a4-ce76da25c4cd