knack.util.ensure_dir can cause race conditions

This checks if a directory exists and then calls mkdir to create it. During automation or scripting where parallelism can come into play this can cause a race condition easily:

knack.util.ensure_dir

def ensure_dir(d):
    """ Create a directory if it doesn't exist """
    if not os.path.isdir(d):
        os.makedirs(d)

To prevent this race condition, use try/expect: to create the directory, then ignore "File exists" errors, which mean the directory was there.

 try:
        os.makedirs(path)
except OSError as e:
        if e.errno != errno.EEXIST:
            raise

Or for 3.2+

os.makedirs('/path/to/dir', exist_ok=True)  

Start at the knack.util.ensure_dir entry point shown in the issue and inspect how it checks for and creates directories. Exercise parallel calls to identify the failure, then verify that concurrent creation is handled without masking other filesystem errors. Run the project's existing test suite if available and confirm the reported race no longer occurs.