Revisions: Address PHP/JS errors when viewing autosave on imported posts.

Fix an issue where viewing an autosave created on a post without any previous revisions would throw a PHP notice. Also fixes the revision screen which was broken in these cases and showed a console error.

Props iseulde.
Fixes #31249.


Built from https://develop.svn.wordpress.org/trunk@50128


git-svn-id: http://core.svn.wordpress.org/trunk@49807 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/revision.php

@@ -281,7 +281,7 @@ function wp_prepare_revisions_for_js( $post, $selected_revision_id, $from = null
 		$revisions[ $post->ID ] = array(
 			'id'         => $post->ID,
 			'title'      => get_the_title( $post->ID ),
-			'author'     => $authors[ $post->post_author ],
+			'author'     => $authors[ $revision->post_author ],
 			'date'       => date_i18n( __( 'M j, Y @ H:i' ), strtotime( $post->post_modified ) ),
 			'dateShort'  => date_i18n( _x( 'j M @ H:i', 'revision date short format' ), strtotime( $post->post_modified ) ),
 			/* translators: %s: Human-readable time difference. */

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.7-alpha-50127';
+$wp_version = '5.7-alpha-50128';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.