Apparently, the TortoiseSVN official 1.10.0 release (released on April 14th), was built against a -dev version of svn 1.10.0.
After installation (of the 64-bit version), running 'svn --version' on the command line says:
svn, version 1.10.0-dev (under development)
compiled Apr 14 2018, 10:24:15 on x86-microsoft-windows
Also, the About window shows:
Subversion 1.10.0, -dev
--
Johan