Comment 5 for bug 1906322

Same issue.

++lib/tempest:install_tempest:747 /opt/stack/tempest/.tox/tempest/bin/pip install -c /opt/stack/requirements/upper-constraints.txt -r requirements.txt
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

/opt/stack/requirements/upper-constraints.txt File contains many "-e file:///opt/stack/" links. Is there a branch to check out that resolves this?