Simplify directory creation with os.makedirs(..., exist_ok=True)

[Jon Dufresne]

The pattern:

if not os.path.exists(path):
    os.makedirs(path)

Can be simplified to:

os.makedirs(path, exist_ok=True

The exist_ok argument was added in Python 3.2:

​https://docs.python.org/3/library/os.html#os.makedirs

The original pattern also has a potential race condition where a process could create a directory at path after the check but before the os.makedirs() call. If such a race condition were to occur, the Django process would result in a FileExistsError. os.makedirs handles this condition.

[Jon Dufresne]

​https://github.com/django/django/pull/10919

[Tim Graham <timograham@…>]

In 290d8471:

Fixed #30147 -- Simplified directory creation with os.makedirs(..., exist_ok=True).