Make xdist failures were show up correctly

Otherwise, was getting this on a test failure, without any of the normal
traceback info:

INTERNALERROR> OSError: cannot send to <Channel id=1 closed>

Author: carver

tox.ini

@@ -36,7 +36,7 @@ commands=
     native-blockchain-istanbul: pytest {posargs:tests/json-fixtures/blockchain/test_blockchain.py --fork Istanbul}
     native-blockchain-berlin: pytest {posargs:tests/json-fixtures/blockchain/test_blockchain.py --fork Berlin}
     native-blockchain-metropolis: pytest {posargs:tests/json-fixtures/blockchain/test_blockchain.py --fork Metropolis}
-    native-blockchain-transition: pytest {posargs:tests/json-fixtures/blockchain/test_blockchain.py -k BlockchainTests/TransitionTests}
+    native-blockchain-transition: pytest {posargs:tests/json-fixtures/blockchain/test_blockchain.py -k TransitionTests --tx '2*popen//execmodel=eventlet'}
     lint: flake8 {toxinidir}/eth {toxinidir}/tests {toxinidir}/scripts
     lint: mypy -p eth --config-file {toxinidir}/mypy.ini