[firedrake] Installation problem on macOS Mojave (libspatialindex)

Hi all, I've been attempting to install Firedrake using the standard install script, but the installation throws an error when attempting to compile/link libspatialindex. The firedrake-install.log is attached. A couple pieces of pertinent info: 1. I'm running macOS Mojave 10.14.5 with Homebrew Python 3. 2. Although I have a miniconda installation on my system, I did a "conda deactivate" before running the install script, so nothing from miniconda (except the conda binary itself) is in my path. Cheers, Ari