Traceback (most recent call last):
  File "/home/uke/oil/bin/oils_for_unix.py", line 20, in <module>
    import posix_ as posix
ImportError: No module named posix_
devtools/byo.sh: fatal: bin/ysh +o no_exported stdlib/ysh/def-test.ysh  doesn't implement BYO: expected status 66, got 1