I opened the issue #23570: Change "with subprocess.Popen():" (context manager) to ignore broken pipe error.

> FAIL: test_broken_pipe_cleanup (test.test_subprocess.ContextManagerTests)

Serhiy: see existing test_communicate_epipe() and test_communicate_epipe_only_stdin() tests which are now reliable and portable.

You should write more data (2**20 bytes) and set the buffer size to a value larger than the input data, to buffer all data, so the write occurs at stdin.close() in Popen.__exit__().

By the way, instead of an hardcoded value (2**20), support.PIPE_MAX_SIZE may be more appropriate.