Fails to run on pip==20.2b1

[fatalcoder]

Environment Versions

1. OS Type
   Docker with python:3.8.5-slim-buster (debian)
2. Python version: $ python -V
   3.8.5
3. pip version: $ pip --version
   20.2b1
4. pip-tools version: $ pip-compile --version
   5.3.0

Steps to replicate

1. Install pip and pip-tools
2. run pip-compile (even with nothing)

Expected result

requirements.txt file is generated

Actual result

Traceback (most recent call last):
  File "/pyroot/bin/pip-compile", line 8, in <module>
    sys.exit(cli())
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/piptools/scripts/compile.py", line 458, in cli
    results = resolver.resolve(max_rounds=max_rounds)
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 169, in resolve
    has_changed, best_matches = self._resolve_one_round()
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 274, in _resolve_one_round
    their_constraints.extend(self._iter_dependencies(best_match))
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 384, in _iter_dependencies
    dependencies = self.repository.get_dependencies(ireq)
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/local.py", line 75, in get_dependencies
    return self.repository.get_dependencies(ireq)
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/pypi.py", line 231, in get_dependencies
    self._dependencies_cache[ireq] = self.resolve_reqs(
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/pypi.py", line 171, in resolve_reqs
    reqset.add_requirement(ireq)
  File "/pyroot/lib/python3.8/site-packages/pip/_internal/req/req_set.py", line 113, in add_requirement
    assert install_req.is_direct == (parent_req_name is None), (
AssertionError: a direct req shouldn't have a parent and also, a non direct req should have a parent

Relates to:
pypa/pip#8637

Possible cause:
#1168

Works fine with 20.1.1

root@bba485fc0a15:/project/app# pip-compile requirements.in > requirements.txt
Traceback (most recent call last):
  File "/pyroot/bin/pip-compile", line 8, in <module>
    sys.exit(cli())
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/pyroot/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/pyroot/lib/python3.8/site-packages/piptools/scripts/compile.py", line 458, in cli
    results = resolver.resolve(max_rounds=max_rounds)
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 169, in resolve
    has_changed, best_matches = self._resolve_one_round()
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 274, in _resolve_one_round
    their_constraints.extend(self._iter_dependencies(best_match))
  File "/pyroot/lib/python3.8/site-packages/piptools/resolver.py", line 384, in _iter_dependencies
    dependencies = self.repository.get_dependencies(ireq)
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/local.py", line 75, in get_dependencies
    return self.repository.get_dependencies(ireq)
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/pypi.py", line 231, in get_dependencies
    self._dependencies_cache[ireq] = self.resolve_reqs(
  File "/pyroot/lib/python3.8/site-packages/piptools/repositories/pypi.py", line 171, in resolve_reqs
    reqset.add_requirement(ireq)
  File "/pyroot/lib/python3.8/site-packages/pip/_internal/req/req_set.py", line 113, in add_requirement
    assert install_req.is_direct == (parent_req_name is None), (
AssertionError: a direct req shouldn't have a parent and also, a non direct req should have a parent
root@bba485fc0a15:/project/app# pip --version
pip 20.2b1 from /pyroot/lib/python3.8/site-packages/pip (python 3.8)
root@bba485fc0a15:/project/app# pip install -U pip==20.1
Collecting pip==20.1
  Downloading pip-20.1-py2.py3-none-any.whl (1.5 MB)
     |████████████████████████████████| 1.5 MB 1.7 MB/s
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.2b1
    Uninstalling pip-20.2b1:
      Successfully uninstalled pip-20.2b1
Successfully installed pip-20.1.1
root@bba485fc0a15:/project/app# pip-compile
#
# This file is autogenerated by pip-compile
# To update, run:
#
#    pip-compile
#
pytz==2020.1              # via -r requirements.in

[atugushev]

Hello @fatalcoder,

Thanks for the issue! It's fixed in pypa/pip#8026 and it's not reproducible with pip install -e git+git@github.com:pypa/pip.git#egg=pip anymore.

[atugushev]

Close this due to the bug doesn't reproduce on the released pip-20.2.