[Python-modules-team] Bug#956745: xonsh autopkgtest fails: out of pty devices

[Jonathan Nieder]

Source: xonsh
Version: 0.9.15+dfsg-1
Severity: important
Justification: blocking git security fix from migrating to testing

The xonsh autopkgtest is failing on arm64:

https://ci.debian.net/data/autopkgtest/testing/arm64/x/xonsh/4989133/log.gz
____________________________ xonsh test: test_indir ____________________________
xonsh execution failed
  File "/tmp/autopkgtest-lxc.hzugiy0a/downtmp/autopkgtest_tmp/tests/test_lib/test_os.xsh", line 15, in test_indir
    assert ![pwd].output.strip() != tmpdir
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22621, in subproc_captured_hiddenobject
    return run_subproc(cmds, captured="hiddenobject")
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22546, in run_subproc
    specs = cmds_to_specs(cmds, captured=captured)
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22516, in cmds_to_specs
    _update_last_spec(specs[-1])
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22450, in _update_last_spec
    r, w = pty.openpty() if use_tty else os.pipe()
  File "/usr/lib/python3.8/pty.py", line 30, in openpty
    master_fd, slave_name = _open_terminal()
  File "/usr/lib/python3.8/pty.py", line 60, in _open_terminal
    raise OSError('out of pty devices')
OSError: out of pty devices
___________________________ xonsh test: test_rmtree ____________________________
xonsh execution failed
  File "/tmp/autopkgtest-lxc.hzugiy0a/downtmp/autopkgtest_tmp/tests/test_lib/test_os.xsh", line 29, in test_rmtree
    mkdir rmtree_test
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22621, in subproc_captured_hiddenobject
    return run_subproc(cmds, captured="hiddenobject")
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22546, in run_subproc
    specs = cmds_to_specs(cmds, captured=captured)
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22516, in cmds_to_specs
    _update_last_spec(specs[-1])
  File "/usr/lib/python3/dist-packages/xonsh/__amalgam__.py", line 22450, in _update_last_spec
    r, w = pty.openpty() if use_tty else os.pipe()
  File "/usr/lib/python3.8/pty.py", line 30, in openpty
    master_fd, slave_name = _open_terminal()
  File "/usr/lib/python3.8/pty.py", line 60, in _open_terminal
    raise OSError('out of pty devices')
OSError: out of pty devices
[etc]

pytest               FAIL non-zero exit status 1