pytest.deprecated_call() seems broken in pytest<3.9.x; concretely, it
doesn't work on CPython 3.8.0 with pytest==3.3.2 on Ubuntu 18.04 (#2922).
This is a narrowed reimplementation of the following PR :(
https://github.com/pytest-dev/pytest/pull/4104
Definition at line 18 of file env.py.