setup.py files with package names which return functions that can't be resolved must be executed

[techalchemy]

per pypa/pipenv#4292 -- a setup.py with a package name that points at a function, e.g. find_name(), that then opens and reads a file (i.e. the value can't be determined by the AST parser), must be executed instead of returning None.

If we return None, the package will never land in the Pipfile.lock.