Fix the template parts included in patterns

admin/class-create-block-theme-admin.php

@@ -703,6 +703,16 @@ function make_mediatext_block_local ( $block ) {
 		return $block;
 	}
 
+	function add_theme_attr_to_template_part_block ( $block ) {
+		// The template parts included in the patterns need to indicate the theme they belong to
+		if ( 'core/template-part' === $block[ 'blockName' ] ) {
+			$block['attrs']['theme'] = ( $_POST['theme']['type'] === "export" || $_POST['theme']['type'] === "save" )
+			? get_stylesheet()
+			: $_POST['theme']['name'];
+		}
+		return $block;
+	}
+
 	function make_media_blocks_local ( $nested_blocks ) {
 		$new_blocks = [];
 		foreach ( $nested_blocks as $block ) {
@@ -718,6 +728,9 @@ function make_media_blocks_local ( $nested_blocks ) {
 				case 'core/media-text':
 					$block = $this->make_mediatext_block_local( $block );
 					break;
+				case 'core/template-part':
+					$block = $this->add_theme_attr_to_template_part_block( $block );
+					break;
 			}
 			// recursive call for inner blocks
 			if ( !empty ( $block['innerBlocks'] ) ) {