Probably. This is likely worthy of a bug against pex, but it's also really not ideal:

$ pex apache-airflow==1.10.0
**** Failed to install apache-airflow-1.10.0 (caused by: NonZeroExit("received exit code 1 during execution of `['/usr/bin/python3.7', '-', 'bdist_wheel', '--dist-dir=/tmp/tmp9oz6r7sr']` while trying to execute `['/usr/bin/python3.7', '-', 'bdist_wheel', '--dist-dir=/tmp/tmp9oz6r7sr']`")
):
stdout:

stderr:
Traceback (most recent call last):
  File "<stdin>", line 9, in <module>
  File "setup.py", line 124
    async = [
          ^
SyntaxError: invalid syntax


Traceback (most recent call last):
  File "/home/jsirois/.venv/pex/bin/pex", line 11, in <module>
    sys.exit(main())
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/bin/pex.py", line 735, in main
    pex_builder = build_pex(reqs, options, resolver_options_builder)
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/bin/pex.py", line 664, in build_pex
    for resolved_dist in resolveds:
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/resolver.py", line 566, in resolve_multi
    use_manylinux=use_manylinux):
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/resolver.py", line 502, in resolve
    return resolver.resolve(resolvables_from_iterable(requirements, builder))
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/resolver.py", line 300, in resolve
    dist = self.build(package, resolvable.options)
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/resolver.py", line 379, in build
    dist = super(CachingResolver, self).build(package, options)
  File "/home/jsirois/.venv/pex/lib/python3.7/site-packages/pex/resolver.py", line 258, in build
    raise Untranslateable('Package %s is not translateable by %s' % (package, translator))
pex.resolver.Untranslateable: Package SourcePackage('file:///home/jsirois/.pex/build/apache-airflow-1.10.0.tar.gz') is not translateable by ChainedTranslator(WheelTranslator, EggTranslator, SourceTranslator)

It would really help to have a working legit failure repro case.