Option not to close stdin/out/err file descriptors

[karolinepauls]

It's sometimes convenient to drop to PDB/embed IPython REPL in a task.

[karolinepauls]

This would be the way:

https://github.com/benoitc/gunicorn/blob/a86ea1e4e6c271d1cd1823c7e14490123f9238fe/gunicorn/glogging.py#L206-L207