Traceback (most recent call last):
  File "/home/svc-web/webshop/env/bin/pip", line 8, in <module>
    sys.exit(main())
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/cli/main.py", line 73, in main
    command = create_command(cmd_name, isolated=("--isolated" in cmd_args))
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/commands/__init__.py", line 96, in create_command
    module = importlib.import_module(module_path)
  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 24, in <module>
    from pip._internal.cli.req_command import RequirementCommand
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/cli/req_command.py", line 20, in <module>
    from pip._internal.operations.prepare import RequirementPreparer
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/operations/prepare.py", line 16, in <module>
    from pip._internal.distributions import (
  File "/home/svc-web/webshop/env/lib/python3.6/site-packages/pip/_internal/distributions/__init__.py", line 1, in <module>
    from pip._internal.distributions.source import SourceDistribution
ImportError: cannot import name 'SourceDistribution'