The 2x existing macpros running 4x 10.12/Sierra VMs have been reimaged to run 10.13/High Sierra on bare metal (ESXi is gone). The “new” osx nodes have Xcode 10.1 installed, which has the same clang version string as Xcode 10.2, which is installed on the 10.14/Mojave node. I’ve re-enable stack-os-matrix OSX builds and allowed either 10.13 or 10.14, while the nightly/weekly builds will still only run on 10.14.
This is intended as a short term measure as we are currently waiting for 3x additional macminis to be delivered. The goal is to allow stack-os-matrix to build on all supported OSX releases.