I want to “hack” python’s import so that it will first search in the path I specified and fallback to the original if not found.

Below is what I have tried.

CASE 1: The following works:

Files:

.
├── a
│   ├── b.py       # content: x='x'
│   └── c.py       # content: y='y'
├── hack
│   └── a
│       └── b.py   # content: x='hacked'
└── test.py        # content: see below

# test.py
import sys
sys.path.insert(0, 'hack') # insert the hack path

from a.b import x
from a.c import y

print(x, y)

Running test.py gives hacked y as desired, where x is hacked 🙂

CASE 2: However, if there is a __init__.py in a, it will not work.

Files:

.
├── a
│   ├── b.py
│   ├── c.py
│   └── __init__.py # <- NOTE THIS
├── hack
│   └── a
│       └── b.py
└── test.py

Running test.py gives x y, where x is not hacked 🙁

CASE 3: To fix case 2, I tried adding __init__.py to the hack path, but this disables the fallback behavior.

Files:

.
├── a
│   ├── b.py
│   ├── c.py
│   └── __init__.py
├── hack
│   └── a
│       ├── b.py
│       └── __init__.py # <- NOTE THIS
└── test.py

Running test.py raises the following error as there is no c.py in the hack path and it fails to fallback to the original path.

ModuleNotFoundError: No module named 'a.c'

My question is, how to make case 2 work?