ImportError: sys.meta_path is None on repo in script

[pared]

Please provide information about your setup
DVC version(i.e. dvc --version), Platform and method of installation (pip, homebrew, pkg Mac, exe (Windows), DEB(Linux), RPM(Linux))

Dvc installed via pip install -e ."[all,test]" in virtualenv with Python 3.6.8.

Reproduction:

1. Create repo:

#!/bin/bash
rm -rf repo
mkdir repo
cd repo
set -e
set -x

git init >> /dev/null && dvc init -q

2. Try to initialize it in script:

from dvc.repo import Repo
repo = Repo("repo")

3. Result:

Exception ignored in: <object repr() failed>
Traceback (most recent call last):
  File "/home/prd/development/tools/venvs/dvc3.6/lib/python3.6/site-packa
ges/flufl/lock/_lockfile.py", line 331, in __del__
  File "/home/prd/development/tools/venvs/dvc3.6/lib/python3.6/site-packa
ges/flufl/lock/_lockfile.py", line 326, in finalize
  File "/home/prd/development/tools/venvs/dvc3.6/lib/python3.6/site-packa
ges/flufl/lock/_lockfile.py", line 285, in unlock
  File "/home/prd/development/tools/venvs/dvc3.6/lib/python3.6/site-packa
ges/flufl/lock/_lockfile.py", line 312, in is_locked
  File "/home/prd/development/tools/venvs/dvc3.6/lib/python3.6/site-packa
ges/flufl/lock/_lockfile.py", line 459, in _touch
ImportError: sys.meta_path is None, Python is likely shutting down

4. Something to start with:
   if we del repo before the end of the script, the problem does not occur.

[efiop]

@pared this doesn't happen during normal CLI operation, right?

[pared]

@efiop correct, it seems like its in-script use issue.

[efiop]

@Suor FYI ^ , maybe you have any ideas :)

[Suor]

@efiop flufl locks have destructor, heh. It's their issue and they even have it reported 7 months ago, with no reaction.

We can use workaround provided there or just make .__del__() noop, not sure we need it.