How to recover from broken sync - request for improving error message

[WolfgangFahl]

Issue

tox runs into downstream virtualenv copy issue.
This happened after the source disk of the snc was full. When disk space was released again the problem persists. The sync does not recover from the problem.The error message is not helpful.

Environment

Provide at least:

• OS: Ubuntu 20.04.LTS
• pip list of the host python where virtualenv is installed:

virtualenv                    20.14.0

Traceback (most recent call last):
File "/usr/local/lib/python3.9/dist-packages/virtualenv/seed/embed/via_app_data/via_app_data.py", line 57, in _install
  installer.install(creator.interpreter.version_info)
File "/usr/local/lib/python3.9/dist-packages/virtualenv/seed/embed/via_app_data/pip_install/base.py", line 39, in install
  self._sync(filename, into)
File "/usr/local/lib/python3.9/dist-packages/virtualenv/seed/embed/via_app_data/pip_install/copy.py", line 13, in _sync
  copy(src, dst)
File "/usr/local/lib/python3.9/dist-packages/virtualenv/util/path/_sync.py", line 52, in copy
  method(norm(src), norm(dest))
File "/usr/local/lib/python3.9/dist-packages/virtualenv/util/path/_sync.py", line 63, in copytree
  shutil.copy(src_f, dest_f)
File "/usr/lib/python3.9/shutil.py", line 427, in copy
  copyfile(src, dst, follow_symlinks=follow_symlinks)
File "/usr/lib/python3.9/shutil.py", line 277, in copyfile
  _fastcopy_sendfile(fsrc, fdst)
File "/usr/lib/python3.9/shutil.py", line 172, in _fastcopy_sendfile
  raise err
File "/usr/lib/python3.9/shutil.py", line 152, in _fastcopy_sendfile
  sent = os.sendfile(outfd, infd, offset, blocksize)
OSError: [Errno 5] Input/output error:

some obscure file in the wheel/3.9 directory

[WolfgangFahl]

as a workaround i had to remove the wheel/3.9 directory

[gaborbernat]

as a workaround i had to remove the wheel/3.9 directory

This is one option, alternatively you can also use https://virtualenv.pypa.io/en/latest/cli_interface.html#reset-app-data