The script is trying to find chown in a cross-platform-like
way, but there's some sort of deficiency in `command -p` in
the default macOS bash 3.2. It looks like it will just use
whatever PATH is already set, instead of the "default" path.
This attempts to hard-set a PATH via `getconf PATH`. It will
just set an empty PATH if that fails for some reason. A
properly-functioning `command -p` should not care what we
set the PATH to here one way or the other.
Hopefully fixes#5768.
bdb5e03821