Brew won't upgrade on Mojave

Same situation. Also just got an update through Software Update for Command Line Tools for Xcode 10 Beta 3.

I installed that and re-installed updated SDK headers and brew config now shows CLT headers, yeah!

Just got an update through Software Update for Command Line Tools for Xcode 10 Beta 3.

I installed that and re-installed SDK headers and it now works.

It's weird that it doesn't show up in https://developer.apple.com/download/more/