Comment 11 for bug 1863414

We can reproduce following command:

$ sudo py3compile -p python3-apport -V 3.0-
/usr/lib/python3.8/subprocess.py:838: RuntimeWarning: line buffering (buffering=1) isn't supported in binary mode, the default buffer size will be used
  self.stdin = io.open(p2cwrite, 'wb', bufsize)

py3comipe set "bufsize=1" for subprocess.Popen(): https://salsa.debian.org/cpython-team/python3-defaults/blob/master/py3compile#L132-133

    process = Popen(cmd, bufsize=1, shell=True,
                    stdin=PIPE, close_fds=True)

However newer python (from 3.8?) warn on buffering=1.

* https://github.com/python/cpython/commit/a2670565d8f5c502388378aba1fe73023fd8c8d4
* https://bugs.python.org/issue32236