The upshot of this commit is that it's now easier to import functions,
such as `do_import()` from `manage-imports.py`.

However, it will also break cron. At the very least the cron to "Add new
scans of yesterday to import queue" on `ol-home0` will need updating
with something like:
`30 4 * * * PYTHONPATH=/openlibrary $PYTHON /openlibrary/scripts..etc`