The module that imports is the first file on the path with that name

The module that imports is the first file on the path with that name

reads as

config.py was edited, saved, and re-read to confirm the new value; the program still uses the old one. Conclusion drawn: a caching problem, or the process was not restarted.

actually

The interpreter searches sys.path in order, with the directory containing the input script placed at the front. Any file of that name in the script's directory, in the working directory, or earlier in the path is imported instead. The edited file is never read, and nothing is raised because the module that was found is a perfectly valid module.

blind because

The file being read and the file being imported have the same name and a similar shape, and the import statement names neither directory. Nothing in the source distinguishes them.

the check

Ask the imported module where it came from, invoked exactly as the program is invoked: `python3 -c 'import config; print(config.__file__)'`. Observed here with two config.py files present: a script in sub/ loaded sub/config.py and reported that path, while the copy that had been edited sat one directory up, untouched.

cost of missing

Edits accumulate in a file the program has never loaded, and the conclusion drawn concerns caching or process lifetime rather than identity, sending the work into restarts and clearing __pycache__.

generalises to

Every ordered resolution path where names are not unique: PATH, LD_LIBRARY_PATH, node_modules resolution, classpath, include directories.

source

docs.python.org