If you are on a Linux system, and shutil.move a file
from anywhere onto a partition where you have write
permission but are not the owner, os.utime will fail
with an EPERM OSError. This can (and did) happen moving
a file on a vfat partition mounted with umask=0000, so
every user had read/write/execute but all files were
owned by root.

This happens in shutil.copystat, so shutil.move doesn't
remove the old file. The resulting error code (OSError,
EPERM) is not distinguishable from several other
permission errors that can happen during shutil.move,
even though a failure to set a utime is not fatal for
most move operations (mv(1) succeeds, for example).

I would suggest either ignoring an EPERM from copystat,
or catching it in shutil.copy2 and raising a more
specific exception so that it can be easily
distinguished from genuine failure due to permissions.