stream_preview_image() should stream with right mime type, if filter _load_image_to_edit_path change file with different mime type

[Hrohh]

Hi, im working on allowing image editor for PDF thumnbails https://core.trac.wordpress.org/ticket/62712.

in functiion stream_preview_image() in wp-admin/includes/image-edit.php - line 766
is function with filter

<?php
_load_image_to_edit_path( $post_id )

we can change filepath, but for example if we change to

metadata['sizes']['full']

which has mimetype image/jpg, function stream_preview_image() dont send image to browser. Bug is in

<?php
return wp_stream_image( $img, $post->post_mime_type, $post_id );

should be

<?php
return wp_stream_image( $img, $img['mime-type'], $attachment_id );