Infinte recursion on Windows+IPython if caller path on drive different than working path

[jdranczewski]

When the imported file calling config is for example on the D: drive, the recurrent function that searches its parent folders will eventually reach D:/. Unfortunately, the check that's meant to stop the recursion considers the drive of the working directory (say, C:/) to be the top folder in some circumstances. The offending lines are these:

python-decouple/decouple.py

Lines 220 to 223 in 0573e6f

	# search the parent
	parent = os.path.dirname(path)
	if parent and os.path.normcase(parent) != os.path.normcase(os.path.abspath(os.sep)):
	return self._find_file(parent)

This results in a silent crash of whatever code is running, but only when the working directory is on a drive different than the drive where the file using config is, I think? It also only happens in IPython, which may be handling working directories differently. This made it quite amusing to diagnose (I was using a different library that imports decouple), and I presume it may make it difficult to reproduce easily.

I suggest replacing the check with:

os.path.normcase(parent) != os.path.normcase(path)

which will catch if the parent is the same as the current path more explicitly.

[jdranczewski]

Ah, the different behaviour under Python and IPython is because on my machine Python correctly raises the RecursionError, which gets caught by the try ... except block in _load, but in IPython the recursion Exception is not raised correctly and the process crashes. This seems to be an issue in IPython: ipython/ipython#12197

So it's both a problem of the recursion happening and IPython handling it badly.