ContextualVersionConflict: pytest 5.3.3 (…/.tox/…-xdist…/lib/python3.6/site-packages), Requirement.parse('pytest!=5.3.3,>=3.6'), {'pytest-django'}

[blueyed]

Trying to skip pytest 5.3.3 via:

     install_requires=[
-        'pytest>=3.6',
+        'pytest>=3.6, !=5.3.3',
         'pathlib2;python_version<"3.4"',
     ],

I see:

$ python -m tox
py36-dj20-postgres-xdist-coverage create: /home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage
py36-dj20-postgres-xdist-coverage installdeps: Django>=2.0,<2.1, psycopg2-binary, coverage-enable-subprocess, pytest-xdist>=1.15
py36-dj20-postgres-xdist-coverage develop-inst: /home/travis/build/pytest-dev/pytest-django
ERROR: invocation failed (exit code 2), logfile: /home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/log/py36-dj20-postgres-xdist-coverage-2.log
================================== log start ===================================
Obtaining file:///home/travis/build/pytest-dev/pytest-django
ERROR: Exception:
Traceback (most recent call last):
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/req/req_install.py", line 441, in check_if_exists
    self.satisfied_by = pkg_resources.get_distribution(str(no_marker))
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 481, in get_distribution
    dist = get_provider(dist)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 357, in get_provider
    return working_set.find(moduleOrReq) or require(str(moduleOrReq))[0]
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pip._vendor.pkg_resources.ContextualVersionConflict: (pytest 5.3.3 (/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages), Requirement.parse('pytest!=5.3.3,>=3.6'), {'pytest-django'})
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/cli/base_command.py", line 153, in _main
    status = self.run(options, args)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 382, in run
    resolver.resolve(requirement_set)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 201, in resolve
    self._resolve_one(requirement_set, req)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 365, in _resolve_one
    abstract_dist = self._get_abstract_dist_for(req_to_install)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 295, in _get_abstract_dist_for
    req, self.require_hashes, self.use_user_site, self.finder,
    req.check_if_exists(use_user_site)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_internal/req/req_install.py", line 452, in check_if_exists
    self.req.name
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 481, in get_distribution
    dist = get_provider(dist)
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 357, in get_provider
    return working_set.find(moduleOrReq) or require(str(moduleOrReq))[0]
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pip._vendor.pkg_resources.ContextualVersionConflict: (pytest 5.3.3 (/home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/lib/python3.6/site-packages), Requirement.parse('pytest!=5.3.3,>=3.6'), {'pytest-django'})
=================================== log end ====================================
___________________________________ summary ____________________________________
ERROR:   py36-dj20-postgres-xdist-coverage: InvocationError for command /home/travis/build/pytest-dev/pytest-django/.tox/py36-dj20-postgres-xdist-coverage/bin/python -m pip install --exists-action w -e '/home/travis/build/pytest-dev/pytest-django[testing]' (exited with code 2)
The command "python -m tox" exited with 1.

This happens for all factors using "xdist" only, but not with Python 2.7.
Builds: https://travis-ci.org/pytest-dev/pytest-django/builds/638643975
PR: pytest-dev/pytest-django#803

From a quick guess it looks like the "xdist" factor pulls in the latest pytest (5.3.3), which then is rejected via setup.py?

I cannot reproduce this locally.

[blueyed]

Fix/workaround:

diff --git a/tox.ini b/tox.ini
index e1dcb5f..acb7480 100644
--- a/tox.ini
+++ b/tox.ini
@@ -32,6 +32,7 @@ deps =
     pytest41: pytest>=4.1,<4.2
     pytest41: attrs==17.4.0
     xdist: pytest-xdist>=1.15
+    xdist: pytest!=5.3.3

 setenv =
     PYTHONPATH = {toxinidir}:{env:PYTHONPATH:}

[asottile]

duplicate of pypa/pip#988