Cannot pip-compile certain dependencies if psycopg2 is installed

[TjrGithub]

pip-compile cannot compile dependencies under certain circumstances. This setup used to work up to a few days ago. It errors out with:

RuntimeError: No stable configuration of concrete packages could be found for the given constraints after 10 rounds of resolving.
This is likely a bug.

The dependencies to compile need to include dbt.

The venv in which Pip-compile resides, needs to be "pip install -r" installed from a requirements.txt, which itself compiled from the following requirements. Simply installing the requirements with "pip install packagename" is not enough to trigger the bug.

flake8
mypy
pylint
pytest
pydocstyle
pip-tools
path
strictyaml
psycopg2
# bug disappears without psycopg2

Environment Versions

Ubuntu 19.10
Python 3.7.5
pip 20.2 from /venv/lib/python3.7/site-packages/pip (python 3.7)
pip-compile, version 5.3.0

Steps to replicate

docker container run -it -v $(pwd)/requirements.txt:/requirements.txt ubuntu:19.10 /bin/bash  -c \
'apt-get update; 
apt-get install -y python3.7 python3-venv libpq-dev postgresql-client-common postgresql-client-11 python3-dev build-essential;
/usr/bin/python3.7 -m venv venv ;
. venv/bin/activate ; 
pip install --upgrade pip ; 
pip install wheel ; 
pip install -r /requirements.txt ; 
echo 'dbt' > requirements.in ; 
pip-compile requirements.in'

where requirements.txt is the following:

#
# This file is autogenerated by pip-compile
# To update, run:
#
#    pip-compile requirements.in
#
astroid==2.4.2            # via pylint
attrs==19.3.0             # via pytest
click==7.1.2              # via pip-tools
flake8==3.8.3             # via -r requirements.in
importlib-metadata==1.7.0  # via flake8, pluggy, pytest
iniconfig==1.0.1          # via pytest
isort==4.3.21             # via pylint
lazy-object-proxy==1.4.3  # via astroid
mccabe==0.6.1             # via flake8, pylint
more-itertools==8.4.0     # via pytest
mypy-extensions==0.4.3    # via mypy
mypy==0.782               # via -r requirements.in
packaging==20.4           # via pytest
path==15.0.0              # via -r requirements.in
pip-tools==5.3.0          # via -r requirements.in
pluggy==0.13.1            # via pytest
psycopg2==2.8.5           # via -r requirements.in
py==1.9.0                 # via pytest
pycodestyle==2.6.0        # via flake8
pydocstyle==5.0.2         # via -r requirements.in
pyflakes==2.2.0           # via flake8
pylint==2.5.3             # via -r requirements.in
pyparsing==2.4.7          # via packaging
pytest==6.0.1             # via -r requirements.in
python-dateutil==2.8.1    # via strictyaml
ruamel.yaml.clib==0.2.0   # via ruamel.yaml
ruamel.yaml==0.16.10      # via strictyaml
six==1.15.0               # via astroid, packaging, pip-tools, python-dateutil
snowballstemmer==2.0.0    # via pydocstyle
strictyaml==1.0.6         # via -r requirements.in
toml==0.10.1              # via pylint, pytest
typed-ast==1.4.1          # via astroid, mypy
typing-extensions==3.7.4.2  # via mypy
wrapt==1.12.1             # via astroid
zipp==3.1.0               # via importlib-metadata

# The following packages are considered to be unsafe in a requirements file:
# pip

Expected result

pip-compile completes running and outputs a correct requirements.txt for dbt.
...

Actual result

pip crashes:

Traceback (most recent call last):
  File "/venv/bin/pip-compile", line 8, in <module>
    sys.exit(cli())
  File "/venv/lib/python3.7/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/venv/lib/python3.7/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/venv/lib/python3.7/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/venv/lib/python3.7/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/venv/lib/python3.7/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/venv/lib/python3.7/site-packages/piptools/scripts/compile.py", line 458, in cli
    results = resolver.resolve(max_rounds=max_rounds)
  File "/venv/lib/python3.7/site-packages/piptools/resolver.py", line 164, in resolve
    "This is likely a bug.".format(max_rounds=max_rounds)
RuntimeError: No stable configuration of concrete packages could be found for the given constraints after 10 rounds of resolving.
This is likely a bug.

...

[atugushev]

This bug was fixed in pip-tools v5.3.1. See #1192.