From c8ff7f6592b325a89485a3bc7031bf4fb38efe69 Mon Sep 17 00:00:00 2001
From: "Dominik Schilling (ocean90)" <ocean90@git.wordpress.org>
Date: Thu, 28 Sep 2017 16:28:46 +0000
Subject: [PATCH] Embeds: In switched state, restore previous state if no post
 ID is found.

Fixes #40673.

git-svn-id: https://develop.svn.wordpress.org/trunk@41634 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/embed.php               |  4 ++++
 tests/phpunit/tests/oembed/wpOembed.php | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/wp-includes/embed.php b/src/wp-includes/embed.php
index 6040004bac..176988057b 100644
--- a/src/wp-includes/embed.php
+++ b/src/wp-includes/embed.php
@@ -1106,6 +1106,10 @@ function wp_filter_pre_oembed_result( $result, $url, $args ) {
 	$post_id = apply_filters( 'oembed_request_post_id', $post_id, $url );
 
 	if ( ! $post_id ) {
+		if ( $switched_blog ) {
+			restore_current_blog();
+		}
+
 		return $result;
 	}
 
diff --git a/tests/phpunit/tests/oembed/wpOembed.php b/tests/phpunit/tests/oembed/wpOembed.php
index d8d346de11..1f5043c3f2 100644
--- a/tests/phpunit/tests/oembed/wpOembed.php
+++ b/tests/phpunit/tests/oembed/wpOembed.php
@@ -200,4 +200,28 @@ class Tests_WP_oEmbed extends WP_UnitTestCase {
 		$this->assertEquals( $this->pre_oembed_result_filtered, $actual );
 		$this->assertSame( $expected_stack, $actual_stack );
 	}
+
+	/**
+	 * @ticket 40673
+	 * @group multisite
+	 * @group ms-required
+	 */
+	public function test_wp_filter_pre_oembed_result_multisite_restores_state_if_no_post_is_found() {
+		$current_blog_id = get_current_blog_id();
+
+		$user_id = self::factory()->user->create();
+		$blog_id = self::factory()->blog->create( array(
+			'user_id' => $user_id,
+		) );
+
+		$permalink = get_home_url( $blog_id, '/foo/' );
+
+		add_filter( 'pre_oembed_result', array( $this, '_filter_pre_oembed_result' ) );
+		$actual = $this->oembed->get_html( $permalink );
+		remove_filter( 'pre_oembed_result', array( $this, '_filter_pre_oembed_result' ) );
+
+		$this->assertNull( $this->pre_oembed_result_filtered );
+		$this->assertFalse( $actual );
+		$this->assertSame( $current_blog_id, get_current_blog_id() );
+	}
 }