`--tb=short` option ignored when combined with `-n2` and `--looponfail`

[Jasha10]

Pytest's --tb=short option is ignored when combined with the --looponfail and -n2 options of pytest-xdist.

To reproduce:

# foo.py
def a():
    b()

def b():
    c()

def c():
    assert False

# test_foo.py
from foo import a
def test_foo():
    a()

$ pytest --tb=short -n2 --looponfail test_foo.py
...  # long-style traceback displayed, --tb=short option ignored.