from unbuffered (0) to buffering (-1) to match the behavior existing code
expects and match the behavior of the subprocess module in Python 2 to avoid
introducing hard to track down bugs.
child subprocess.PIPE parent file descriptors on child error prior to
exec().
This would lead to race conditions in multithreaded programs where
another thread opened a file reusing the fd which was then closed out
from beneath it by the errant second close.
all together and just include the repr of the data in the exception
itself instead of the useless string "Unknown".
This code path is unlikely to even be possible to take given the
nature of the pipe it gets subprocess data from.
misleading error message stating that args[0] did not exist when
either the cwd or executable keyword arguments specified a path that
did not exist.
It now keeps track of if the child got as far as preexec and reports it if
not back to the parent via a special "noexec" error message value in
the error pipe so that the cwd can be blamed for a failed chdir
instead of the exec of the executable being blamed instead.
The executable is also always reported accurately when exec fails.
Unittests enhanced to cover these cases.
module: the piped streams can now be properly read from or written to.
(this was broken due to the 2.x to 3.x transition; communicate() support
is still sketchy)
