[docs] [issue13286] PEP 3151 breaks backward compatibility: it should be documented

[STINNER Victor]

New submission from STINNER Victor <victor.stinner at haypocalc.com>:

The following example works on Python 2.7 and 3.2, but fails on Python 3.3:
-----------
import errno
import os

try:
    os.rmdir("testdir")
except:
    pass
os.mkdir("testdir")

try:
    try:
        os.mkdir("testdir")
    except IOError as exc:
        # If can't get proper access, then just forget about writing
        # the data.
        if exc.errno == errno.EACCES:
            pass
        else:
            raise
    except OSError as exc:
        # Probably another Python process already created the dir.
        if exc.errno == errno.EEXIST:
            pass
        else:
            raise
except Exception:
    print("PEP 3151 broke backward compatibility on such pattern!")
-----------

I noticed the problem while reading the changeset e4d44c2e8e81.

----------
assignee: docs at python
components: Documentation
messages: 146562
nosy: docs at python, flox, haypo, pitrou
priority: normal
severity: normal
status: open
title: PEP 3151 breaks backward compatibility: it should be documented
versions: Python 3.3

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue13286>
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