Where is the istio $PATH set in mac/osx?

Each time I upgrade istio, it sets an additional $PATH for the new bin. For the world I cannot figure where the istio installer changed the $PATH for all shells. So far, I’ve searched:

/etc/bashrc
/etc/profile
~/.bashrc
~/.bash_profile
~/.profile
~/.MacOSX/environment.plist
/etc/paths
/etc/paths.d/

with absolutely no luck.  In .zshrc, I can set $PATH="", then add my env back in, but that's dumb and doesn't fix the problem for the next install.  

Sorry guys for the elementary Q, but this one is driving me crazy.  Any ideas please?

Thanks!

How are you doing the upgrade? Maybe using brew. I’m not sure who owns that.