I also saw this change on my Mac when I went from running pip to sudo pip. Adding -H to sudo causes the message to go away for me. E.g.
sudo -H pip install foo
man sudo tells me that -H causes sudo to set $HOME to the target users (root in this case).
So it appears pip is looking into $HOME/Library/Log and sudo by default isn’t setting $HOME to /root/. Not surprisingly ~/Library/Log is owned by you as a user rather than root.
I suspect this is some recent change in pip. I’ll run it with sudo -H for now to work around.