fix test result output on Windows (#951)
fix test result output on Windows (#951)

* fix test result output on Windows

Using `call` swallows the exit code of the test runner, making
Jenkins mark failed test runs as unstable instead of failed.

* exit if pytest fails

* set error code explicitly

beniwohli/apm-agent-python,beniwohli/apm-agent-python,beniwohli/apm-agent-python,beniwohli/apm-agent-python