One way around it is using pathlib. It has a backport for Python 2 and its mkdir() function supports exist_ok.
try:
from pathlib import Path
except ImportError:
from pathlib2 import Path # python 2 backport
Path(settings.STATIC_ROOT).mkdir(exist_ok=True)
As the comment suggests, use parents=True for makedirs().
Path(settings.STATIC_ROOT).mkdir(exist_ok=True, parents=True)