warn specific classes (#361)
warn specific classes (#361)

* warn specific classes

* Update src/pytest_cov/plugin.py

* Update src/pytest_cov/compat.py

* Update src/pytest_cov/compat.py

* Update src/pytest_cov/compat.py

* Update src/pytest_cov/plugin.py

* Update src/pytest_cov/plugin.py
pytest-dev/pytest-cov