Postgres 9.4 via Homebrew on macOS

I needed to run an old version of Postgres in order to be supported by the version of Rails I was working with, and I had a new Mac with High Sierra installed. Found out after a bit of "Why doesn't this postgres formula link its executables?" that it was precisely because of the age of the version that it wasn't linking. (In my old Linux days I would have just automatically added the PATH or made the link, but I also would have probably rebuilt the Linux install within a few months, anyway.)