django_find_project: inconsistent behavior with args

[blueyed]

The django_find_project option will not check for a Django project (manage.py) if run via pytest -k foo, since it will only look for manage.py from "foo".

The main issue here is: foo is not a file, but the value for the -k option, it should behave as with just pytest here. This requires to actually look at parsed args/options and not the raw args.

As a workaround we should add cwd always for the check (last), as with just using pytest.

[blueyed]

Improved via #690, but leaving it open, because it is still a hack.