BUT, I disconcur on your local testing?:
$ ./pants filedeps tests/python/pants_test:test_infra | grep pex
/home/jsirois/dev/pantsbuild/pants/tests/python/pants_test/testutils/pexrc_util.py
/home/jsirois/dev/pantsbuild/pants/src/python/pants/backend/python/tasks/pex_build_util.py