This is a future test build--the same as Version 528, but it uses new libraries. Please feel free to test and let me know if you cannot boot or otherwise get weird errors. As always, make a backup before you test anything on a real database you care about.
Note: To update an existing build that is not a 'future' version, or vice versa, you may need to perform a clean install, as here. I would be very interested in knowing if you do!
If you have the 'new pages take two seconds to open' problem since 526 or so, this may fix you.