BOINC 7.8.6 for Mac OS is now available on the primary BOINC Download Site:

https://boinc.berkeley.edu/download_all.php

From Charlie Fenton ...

This is a release for Macintosh only; there are no changes from 7.8.3, 7.8.4 or 7.8.5 affecting the code for any other platform. It fixes a couple of Mac-only bugs in 7.8.5:
* Reliably installs the BOINC screensaver (unless asked not to do so.)
* Fixes a bug which could prevent determining the correct size of RAM when run on versions of OS X older than OS 10.11.