subprocess._USE_VFORK doesn't change usage of vfork #121381
Description
Bug report
Bug description:
Discussion: https://discuss.python.org/t/subprocess-use-vfork-escape-hatch-broken-fix-or-remove/56915
This flag was added as an escape hatch in gh-91401 and backported to Python 3.10. The flag broke at some point between its addition and now. As there is currently no publicly known environments that require this, planning to remove it rather than work on fixing it.
I found that the test for this was broken while working on tests for reducing system calls in other cases (GH-120754). The strace based test isn't currently being run by any CI bots. Have a PR which both adds tests around read and fixes the strace tests to run on some of the bots: #121143
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux