$ pip install git+https://github.com/pytest-dev/pluggy.git@master pygments 'pytest-xdist>=1.13'
Collecting git+https://github.com/pytest-dev/pluggy.git@master
  Cloning https://github.com/pytest-dev/pluggy.git (to revision master) to /tmp/pip-req-build-e8b28ihx
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
    Preparing wheel metadata ... done
Collecting pygments
  Using cached Pygments-2.7.3-py3-none-any.whl (950 kB)
Collecting pytest-xdist>=1.13
  Using cached pytest_xdist-2.1.0-py3-none-any.whl (36 kB)
Collecting execnet>=1.1
  Using cached execnet-1.7.1-py2.py3-none-any.whl (39 kB)
Collecting apipkg>=1.4
  Using cached apipkg-1.5-py2.py3-none-any.whl (4.9 kB)
Collecting pytest>=6.0.0
  Using cached pytest-6.1.2-py3-none-any.whl (272 kB)
  Using cached pytest-6.1.1-py3-none-any.whl (272 kB)
  Using cached pytest-6.1.0-py3-none-any.whl (272 kB)
  Using cached pytest-6.0.2-py3-none-any.whl (270 kB)
  Using cached pytest-6.0.1-py3-none-any.whl (270 kB)
  Using cached pytest-6.0.0-py3-none-any.whl (270 kB)
INFO: pip is looking at multiple versions of apipkg to determine which version is compatible with other requirements. This could take a while.
Collecting apipkg>=1.4
  Using cached apipkg-1.4-py2.py3-none-any.whl (6.6 kB)
INFO: pip is looking at multiple versions of execnet to determine which version is compatible with other requirements. This could take a while.
Collecting execnet>=1.1
  Using cached execnet-1.7.0-py2.py3-none-any.whl (38 kB)
  Using cached execnet-1.6.1-py2.py3-none-any.whl (38 kB)
  Using cached execnet-1.6.0-py2.py3-none-any.whl (38 kB)
INFO: pip is looking at multiple versions of apipkg to determine which version is compatible with other requirements. This could take a while.
  Using cached execnet-1.5.0-py2.py3-none-any.whl (39 kB)
  Using cached execnet-1.4.1-py2.py3-none-any.whl (40 kB)
  Using cached execnet-1.4.0-py2.py3-none-any.whl (40 kB)
INFO: This is taking longer than usual. You might need to provide the dependency resolver with stricter constraints to reduce runtime. If you want to abort this run, you can press Ctrl + C to do so. To improve how pip performs, tell us what happened here: https://pip.pypa.io/surveys/backtracking
  Using cached execnet-1.3.0-py2.py3-none-any.whl (39 kB)
INFO: pip is looking at multiple versions of execnet to determine which version is compatible with other requirements. This could take a while.
  Using cached execnet-1.2.0.tar.gz (163 kB)
  Using cached execnet-1.1.zip (324 kB)
INFO: pip is looking at multiple versions of <Python from Requires-Python> to determine which version is compatible with other requirements. This could take a while.
INFO: pip is looking at multiple versions of pytest-xdist to determine which version is compatible with other requirements. This could take a while.
Collecting pytest-xdist>=1.13
  Using cached pytest_xdist-2.0.0-py2.py3-none-any.whl (36 kB)
Collecting psutil>=3.0.0
  Using cached psutil-5.7.3.tar.gz (465 kB)
INFO: pip is looking at multiple versions of psutil to determine which version is compatible with other requirements. This could take a while.
  Using cached psutil-5.7.2.tar.gz (460 kB)
  Using cached psutil-5.7.1.tar.gz (460 kB)
  Using cached psutil-5.7.0.tar.gz (449 kB)
  Using cached psutil-5.6.7.tar.gz (448 kB)
  Using cached psutil-5.6.6.tar.gz (447 kB)
  Using cached psutil-5.6.5.tar.gz (447 kB)
  Using cached psutil-5.6.4.tar.gz (447 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
    Preparing wheel metadata ... done
INFO: pip is looking at multiple versions of psutil to determine which version is compatible with other requirements. This could take a while.
  Using cached psutil-5.6.3.tar.gz (435 kB)
  Using cached psutil-5.6.2.tar.gz (432 kB)
  Using cached psutil-5.6.1.tar.gz (427 kB)
  Using cached psutil-5.6.0.tar.gz (426 kB)
  Using cached psutil-5.5.1.tar.gz (426 kB)
INFO: This is taking longer than usual. You might need to provide the dependency resolver with stricter constraints to reduce runtime. If you want to abort this run, you can press Ctrl + C to do so. To improve how pip performs, tell us what happened here: https://pip.pypa.io/surveys/backtracking
  Using cached psutil-5.5.0.tar.gz (425 kB)
  Using cached psutil-5.4.8.tar.gz (422 kB)
  Using cached psutil-5.4.7.tar.gz (420 kB)
  Using cached psutil-5.4.6.tar.gz (418 kB)
  Using cached psutil-5.4.5.tar.gz (418 kB)
  Using cached psutil-5.4.4.tar.gz (417 kB)
  Using cached psutil-5.4.3.tar.gz (412 kB)
  Using cached psutil-5.4.2.tar.gz (411 kB)
  Using cached psutil-5.4.1.tar.gz (408 kB)
  Using cached psutil-5.4.0.tar.gz (406 kB)
  Using cached psutil-5.3.1.tar.gz (397 kB)
  Using cached psutil-5.3.0.tar.gz (397 kB)
  Using cached psutil-5.2.2.tar.gz (348 kB)
  Using cached psutil-5.2.1.tar.gz (347 kB)
  Using cached psutil-5.2.0.tar.gz (345 kB)
  Using cached psutil-5.1.3.tar.gz (341 kB)
  Using cached psutil-5.1.2.tar.gz (341 kB)
  Using cached psutil-5.1.1.tar.gz (341 kB)
  Using cached psutil-5.1.0.tar.gz (339 kB)
  Using cached psutil-5.0.1.tar.gz (326 kB)
  Using cached psutil-5.0.0.zip (374 kB)
  Using cached psutil-4.4.2.tar.gz (1.8 MB)
  Using cached psutil-4.4.1.tar.gz (1.8 MB)
  Using cached psutil-4.4.0.tar.gz (1.8 MB)
  Using cached psutil-4.3.1.tar.gz (315 kB)
  Using cached psutil-4.3.0.tar.gz (316 kB)
  Using cached psutil-4.2.0.tar.gz (311 kB)
  Using cached psutil-4.1.0.tar.gz (301 kB)
  Using cached psutil-4.0.0.tar.gz (293 kB)
  Using cached psutil-3.4.2.tar.gz (274 kB)
  Using cached psutil-3.4.1.tar.gz (271 kB)
  Using cached psutil-3.3.0.tar.gz (261 kB)
  Using cached psutil-3.2.2.tar.gz (253 kB)
  Using cached psutil-3.2.1.tar.gz (251 kB)
  Using cached psutil-3.2.0.tar.gz (251 kB)
  Using cached psutil-3.1.1.tar.gz (247 kB)
  Using cached psutil-3.1.0.tar.gz (246 kB)
  Using cached psutil-3.0.1.tar.gz (241 kB)
  Using cached psutil-3.0.0.tar.gz (240 kB)
INFO: This is taking longer than usual. You might need to provide the dependency resolver with stricter constraints to reduce runtime. If you want to abort this run, you can press Ctrl + C to do so. To improve how pip performs, tell us what happened here: https://pip.pypa.io/surveys/backtracking
Collecting pytest-xdist>=1.13
  Using cached pytest_xdist-1.34.0-py2.py3-none-any.whl (36 kB)
Collecting pytest>=4.4.0
  Using cached pytest-5.4.3-py3-none-any.whl (248 kB)
  Using cached pytest-5.4.2-py3-none-any.whl (247 kB)
  Using cached pytest-5.4.1-py3-none-any.whl (246 kB)
  Using cached pytest-5.4.0-py3-none-any.whl (247 kB)
  Using cached pytest-5.3.5-py3-none-any.whl (235 kB)
  Using cached pytest-5.3.4-py3-none-any.whl (235 kB)
  Using cached pytest-5.3.3-py3-none-any.whl (235 kB)
  Using cached pytest-5.3.2-py3-none-any.whl (234 kB)
  Using cached pytest-5.3.1-py3-none-any.whl (233 kB)
  Using cached pytest-5.3.0-py3-none-any.whl (233 kB)
  Using cached pytest-5.2.4-py3-none-any.whl (227 kB)
  Using cached pytest-5.2.3-py3-none-any.whl (227 kB)
  Using cached pytest-5.2.2-py3-none-any.whl (227 kB)
  Using cached pytest-5.2.1-py3-none-any.whl (226 kB)
  Using cached pytest-5.2.0-py3-none-any.whl (226 kB)
  Using cached pytest-5.1.3-py3-none-any.whl (224 kB)
  Using cached pytest-5.1.2-py3-none-any.whl (224 kB)
  Using cached pytest-5.1.1-py3-none-any.whl (223 kB)
  Using cached pytest-5.1.0-py3-none-any.whl (223 kB)
  Using cached pytest-5.0.1-py3-none-any.whl (221 kB)
  Using cached pytest-5.0.0-py3-none-any.whl (221 kB)
  Using cached pytest-4.6.11-py2.py3-none-any.whl (231 kB)
  Using cached pytest-4.6.10-py2.py3-none-any.whl (231 kB)
  Using cached pytest-4.6.9-py2.py3-none-any.whl (231 kB)
  Using cached pytest-4.6.8-py2.py3-none-any.whl (230 kB)
  Using cached pytest-4.6.7-py2.py3-none-any.whl (230 kB)
  Using cached pytest-4.6.6-py2.py3-none-any.whl (230 kB)
  Using cached pytest-4.6.5-py2.py3-none-any.whl (230 kB)
  Using cached pytest-4.6.4-py2.py3-none-any.whl (229 kB)
  Using cached pytest-4.6.3-py2.py3-none-any.whl (229 kB)
  Using cached pytest-4.6.2-py2.py3-none-any.whl (229 kB)
  Using cached pytest-4.6.1-py2.py3-none-any.whl (229 kB)
  Using cached pytest-4.6.0-py2.py3-none-any.whl (229 kB)
  Using cached pytest-4.5.0-py2.py3-none-any.whl (227 kB)
  Using cached pytest-4.4.2-py2.py3-none-any.whl (224 kB)
Requirement already satisfied: setuptools in ./venv/lib/python3.9/site-packages (from pytest>=4.4.0->pytest-xdist>=1.13) (51.0.0)
Collecting atomicwrites>=1.0
  Using cached atomicwrites-1.4.0-py2.py3-none-any.whl (6.8 kB)
Collecting attrs>=17.4.0
  Using cached attrs-20.3.0-py2.py3-none-any.whl (49 kB)
Collecting more-itertools>=4.0.0
  Using cached more_itertools-8.6.0-py3-none-any.whl (45 kB)
Collecting py>=1.8.2
  Using cached py-1.9.0-py2.py3-none-any.whl (99 kB)
Collecting pytest-forked
  Using cached pytest_forked-1.3.0-py2.py3-none-any.whl (4.7 kB)
Collecting six
  Using cached six-1.15.0-py2.py3-none-any.whl (10 kB)
Building wheels for collected packages: pluggy
  Building wheel for pluggy (PEP 517) ... done
  Created wheel for pluggy: filename=pluggy-1.0.0.dev42+g0a064fe-py2.py3-none-any.whl size=17167 sha256=75ef8d2ccf6e7c1167980a4ef2bc3c7ff8a166cce18d237a8a0f694b1381a3af
  Stored in directory: /tmp/pip-ephem-wheel-cache-omaoijz3/wheels/11/4f/c5/b06db3d455aa75353e19a9bd471fd4e034dfe2eeb99171dbe7
Successfully built pluggy
Installing collected packages: six, py, pluggy, more-itertools, attrs, atomicwrites, pytest, apipkg, pytest-forked, execnet, pytest-xdist, pygments
Successfully installed apipkg-1.5 atomicwrites-1.4.0 attrs-20.3.0 execnet-1.7.1 more-itertools-8.6.0 pluggy-1.0.0.dev42+g0a064fe py-1.9.0 pygments-2.7.3 pytest-4.4.2 pytest-forked-1.3.0 pytest-xdist-1.34.0 six-1.15.0