fs.copy.copy_file: Breaking changes between Python 3.7 and Python 3.8

[avivace]

On Python 3.7.1 with fs==2.4.12, this doesn't work:

import fs
my_fs = fs.open_fs("/")
fs.copy.copy_file(
   src_fs=my_fs,
   dst_fs=my_fs,
   src_path="/tmp/1.txt",
   dst_path="/tmp/42"
)

raising IsADirectoryError: [Errno 21] Is a directory: '/tmp/42'.

However, the same snippet succeds in Python 3.8.0 with the same version of fs. It appears that while running on Python 3.7.x the dst path must have the file name, while on 3.8.0 it can be a directory. Is this expected?

[althonos]

Thanks for the report! That's definitely not expected, as we try to get a consistent behaviour on all platforms.

Internally, OSFS.copy uses shutil.copy2 if it is supported, which changed in Python 3.8 with added support for platform-specific copy operations. I'd think for consistency PyFilesystem2 would want to check that dst_path is not a directory.