resmgr download directories

[bertsky]

If I do

ocrd resmgr download -a -n ~/.local/share/ocrd-resources/ocrd-origami-segment/bbz ocrd-origami-segment bbz2

then I end up with

  File "/ocrd_all/core/build/__editable__.ocrd-2.65.0-py3-none-any/ocrd/cli/resmgr.py", line 155, in download
    fpath = resmgr.download(
  File "/ocrd_all/core/build/__editable__.ocrd-2.65.0-py3-none-any/ocrd/resource_manager.py", line 314, in download
    self._copy_impl(url, fpath, progress_cb)
  File "/ocrd_all/core/build/__editable__.ocrd-2.65.0-py3-none-any/ocrd/resource_manager.py", line 257, in _copy_impl
    with open(child_dst, 'wb') as f_out, open(child, 'rb') as f_in:
IsADirectoryError: [Errno 21] Is a directory: '~/.local/share/ocrd-resources/ocrd-origami-segment/bbz/v3'

See this older comment

[bertsky]

And this older review says the culprit is here:

https://github.com/OCR-D/core/blob/01955620274e461a8470b37404ef1e9996ca3221/src/ocrd/resource_manager.py#L249-L265

This is not recursive (enough): it cannot copy with subdirectories.