Manual build, runtime permissions errors

```text
$ fonttools --help
... noise ...
PermissionError: [Errno 13] Permission denied: '/usr/lib/python3.6/site-packages/ufonormalizer-0.3.6-py3.6.egg-info/PKG-INFO'
```

Looks similar to https://bugs.launchpad.net/dateutil/+bug/1243202