This significantly reduces the time taken to run the test suite (on the
unix port). Use `-j1` to disable this feature.
Signed-off-by: Jeff Epler <jepler@gmail.com>
Commit cb68a5741a broke automatic Python
feature detection when running tests, because some detection relied on a
crash of a feature script returning exactly b"CRASH".
This commit fixes this and improves the situation by testing for the lack
of a known pass result, rather than an exact failure result.
Signed-off-by: Damien George <damien@micropython.org>
