Bug in wp_update_post()

This plugin demonstrates bug in wp_update_post().

Activate it on clean WP. Plugin creates two tags with slugs wp_update_post_tag_1 and wp_update_post_tag_2 and the same name wp_update_post_tag.

Go to /wpup-test/ page of your site. You will see output like that

wp_get_post_tags() Before wp_update_post()

array (size=1)
  0 => 
        object(WP_Term)[312]
          public 'term_id' => int 39
          public 'name' => string 'wp_update_post_tag' (length=18)
          public 'slug' => string 'wp_update_post_tag_2' (length=20)
          public 'term_group' => int 0
          public 'term_taxonomy_id' => int 39
          public 'taxonomy' => string 'post_tag' (length=8)
          public 'description' => string '' (length=0)
          public 'parent' => int 0
          public 'count' => int 1
          public 'filter' => string 'raw' (length=3)
    
    wp_get_post_tags() After wp_update_post()
    
    array (size=1)
      0 => 
        object(WP_Term)[314]
          public 'term_id' => int 38
          public 'name' => string 'wp_update_post_tag' (length=18)
          public 'slug' => string 'wp_update_post_tag_1' (length=20)
          public 'term_group' => int 0
          public 'term_taxonomy_id' => int 38
          public 'taxonomy' => string 'post_tag' (length=8)
          public 'description' => string '' (length=0)
          public 'parent' => int 0
          public 'count' => int 1
          public 'filter' => string 'raw' (length=3)

tag attached to the post has changed.

And that's nice.