Windows 10 build 17713 (rs prerelease)

Windows 10 build 17713 (rs prerelease) is an unleaked build of Windows 10 May 2019 Update. A  image of this build for demonstrating the Web Sign-in feature of Windows was found in the release announcement for October 2018 Update build 17713.

Source

 * Official announcement for October 2018 Update build 17713