CI: still seeing "fatal: unsafe repository"

```
fatal: unsafe repository ('/home/jovyan/octsympy' is owned by someone else)
To add an exception for this directory, call:
	git config --global --add safe.directory /home/jovyan/octsympy
```
Maybe we need to `git config` as well (or instead) of `sudo git config`...   At least I don't think that "global" thing means "all users".  More like "all repos"