Index: tests/phpunit/tests/comment/commentsTemplate.php
===================================================================
--- tests/phpunit/tests/comment/commentsTemplate.php	(revision 36269)
+++ tests/phpunit/tests/comment/commentsTemplate.php	(working copy)
@@ -728,4 +728,46 @@
 		$found_cids = array_map( 'intval', $matches[1] );
 		$this->assertSame( array( $comment_2, $comment_3, $comment_1 ), $found_cids );
 	}
+
+	/*
+	 * @ticket 35419
+	 */
+	public function test_comment_parent_should_be_ignored_when_threading_is_disabled() {
+		$now = time();
+		$p = self::factory()->post->create();
+		$comment_1 = self::factory()->comment->create( array(
+			'comment_post_ID' => $p,
+			'comment_content' => '1',
+			'comment_approved' => '1',
+			'comment_date_gmt' => date( 'Y-m-d H:i:s', $now - 300 ),
+		) );
+		$comment_2 = self::factory()->comment->create( array(
+			'comment_post_ID' => $p,
+			'comment_content' => '2',
+			'comment_approved' => '1',
+			'comment_date_gmt' => date( 'Y-m-d H:i:s', $now - 200 ),
+		) );
+		$comment_3 = self::factory()->comment->create( array(
+			'comment_post_ID' => $p,
+			'comment_content' => '3',
+			'comment_approved' => '1',
+			'comment_parent' => $comment_1,
+			'comment_date_gmt' => date( 'Y-m-d H:i:s', $now - 100 ),
+		) );
+
+		update_option( 'comment_order', 'asc' );
+		update_option( 'thread_comments', 0 );
+		update_option( 'comments_per_page', 2 );
+		update_option( 'page_comments', 1 );
+		update_option( 'default_comments_page', 'newest' );
+
+		$this->go_to( get_permalink( $p ) );
+		$found = get_echo( 'comments_template' );
+
+		// Find the found comments in the markup.
+		preg_match_all( '|id="comment-([0-9]+)|', $found, $matches );
+
+		$found_cids = array_map( 'intval', $matches[1] );
+		$this->assertSame( array( $comment_3 ), $found_cids );
+	}
 }