check_outdir() can crash with OSError: [Errno 17] File exists

[Thomas Gilgenast]

This seems to happen when running on the cluster at times when the cluster is slow.

Specifically, the call to os.path.exists() returns False, but the call to os.makedirs() still raises OSError: [Errno 17] File exists.

Typical console output includes

creating directory <some_directory>
...
OSError: [Errno 17] File exists: '<some_directory>'

We could dodge this with a try-catch block catching the OSError.

[Thomas Gilgenast]

fixed by b8b98ae