Thank you for the report!

I agree, FTPHost.makedirs should accept the exist_ok argument, as os.makedirs does.

When looking at the code, I noticed that the current implementation doesn't accept an exist_ok argument, but behaves as if exist_ok=True was given. However, according to the documentation at ​https://docs.python.org/3/library/os.html#os.makedirs , exist_ok should be False by default.

I plan to change the behavior in a future ftputil 4.0.0, so that makedirs without exist_ok conforms to the Python documentation and the exist_ok argument is supported.

Fixed in a2843e387f3c3d6e17a8ef2fcf3a25df1006d761.

As I meanwhile noticed, the earlier behavior of makedirs in ftputil wasn't a bug, but the actual semantics of os.makedirs in Python 2. On the other hand, Python 3 not only adds the argument exist_ok, but also chooses the default so that the default behavior is different from that in Python 2.

So this issue has to be listed under the backward-incompatible changes in the documentation and in the announcement.