# PIP_VIRTUAL_ENV=/opt/stack/requirements/.venv env http_proxy= https_proxy= no_proxy= PIP_FIND_LINKS= SETUPTOOLS_SYS_PATH_TECHNIQUE=rewrite /opt/stack/requirements/.venv/bin/pip install -c /opt/stack/requirements/upper-constraints.txt -U pbr
DEPRECATION: Constraints are only allowed to take the form of a package name and a version specifier. Other forms were originally permitted as an accident of the implementation, but were undocumented. The new implementation of the resolver no longer supports these forms. A possible replacement is replacing the constraint with a requirement.. You can find discussion regarding this at https://github.com/pypa/pip/issues/8210.
ERROR: Links are not allowed as constraints