os.replace may fail if multiple file systems are involved

[jhidding]

See https://docs.python.org/3/library/os.html#os.replace

I got the following error:

OSError: [Errno 18] Invalid cross-device link: '/tmp/tmp43rpme1y' -> 'loom/lazy.py'

[jhidding]

I'll use the dir= argument to create the temporary file in a local place.