Ticket #19907: 19907.patch

wp-admin/includes/post.php

@@ -223 +223 @@
                 }
         }
 
+        // Drafts shouldn't be assigned a date unless explicitly done so by the user
+        if ( in_array( $post_data['post_status'], array( 'draft', 'pending', 'auto-draft' ) ) && !empty( $post_data['post_date'] ) && $post_data['post_date'] == $post->post_date )
+                $post_data['post_date_gmt'] = '';
+
         add_meta( $post_ID );
 
         update_post_meta( $post_ID, '_edit_last', $GLOBALS['current_user']->ID );