### Problem:
parsing of plugin args breaks after having any path-like argument (`--atf --atf-file /dev/null` works, but `--atf --atf-file /dev/null --atf-cleanup` does not).
Pytest issues: [3097](https://github.com/pytest-dev/pytest/issues/3097), [6904](https://github.com/pytest-dev/pytest/issues/6904) and probably others.
This diff implements the suggested workaround - passing values in form `--arg=value` instead of `--arg value`.