I don’t think we patch 3.2 or 3.3 any more unless it is a security concern. That is why I removed them. I understand 3.4 is due for its last non-security release in a couple weeks.

I was actually referring to your original suggestion in <https://bugs.python.org/issue25583#msg254339>, dressed up below:

except OSError:
    # Cannot rely on checking for EEXIST, since the operating system could give priority to other errors like EACCES or EROFS
    if not (exist_ok and path.isdir(name)):
        raise

There may be practical reasons to continue if a parent directory exists on a read-only FS. Some OSes can mount writable FSes inside read-only FSes. See <https://marc.info/?l=coreutils-bug&m=124770585425870&w=2> involving Cygwin, and <https://marc.info/?l=linux-kernel&m=120998905229849&w=2> involving a Linux regression.

Anyway, I think I am happy with either your last fix or the first, with an appropriate comment, and hopefully also a test case.