Racy copr-common testsuite

[praiskup]

=================================== FAILURES ===================================
__________________________ test_posix_live_output_cut __________________________

    def test_posix_live_output_cut():
        cmd = ["bash", "-c", "echo aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"]
        proc = PosixPipedProcess(cmd, stdout_limit=10)
        outs = {"stdout": "", "stderr": ""}
        for chunk, out in proc.readchunks():
            outs[out] += chunk.decode("utf8")
>       assert proc.returncode == 0
E       assert -9 == 0
E        +  where -9 = <copr_common.subprocess_live_output.PosixPipedProcess object at 0x7fff96436b70>.returncode

tests/test_popen_live_output.py:82: AssertionError
=============================== warnings summary ===============================
copr_common/request.py:7
  /builddir/build/BUILD/python-copr-common-0.22/copr_common/request.py:7: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
    import pkg_resources

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED tests/test_popen_live_output.py::test_posix_live_output_cut - assert -...
==================== 1 failed, 9 passed, 1 warning in 2.66s ====================
error: Bad exit status from /var/tmp/rpm-tmp.GL9RzE (%check)

[nikromen]

I think this was error in rawhide, but if this will appear in stable fedoras, please reopen this and add more context.