Intermodule importing using `import` not working (`from ... import ...` works fine)

Importing a module from within the same directory works fine. Importing a module from another directory using PYTHONPATH also (mostly) works. But, if a module (with PYTHONPATH) imports another module from the same package (directory) using the `import` syntax, that doesn't seem to work.

## Regression

Using the `from X import Y` syntax works fine.