Pip: Test suite fails collection due to svn check

Environment

• pip version: 720c77aa
• Python version: 3.8.1
• OS: macOS Catalina 10.15.4

Description

This week, I upgraded to macOS 10.15.4. Now, when I run svn --version, I see this error:

pip master $ svn --version                                                                                                                                                
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.

When I run the pip test suite, I see similar errors during test discovery, which causes the whole test suite not to run.

Expected behavior

Tests for svn really shouldn't block tests.

How to Reproduce

Presumably:

1. Update to macOS 10.15.4.
2. Run tox.

Output

$ tox
GLOB sdist-make: /Users/jaraco/code/public/pypa/pip/setup.py
python inst-nodeps: /Users/jaraco/code/public/pypa/pip/.tox/.tmp/package/1/pip-20.1.dev0.zip
python installed: apipkg==1.5,atomicwrites==1.3.0,attrs==19.3.0,cffi==1.14.0,coverage==5.0.4,cryptography==2.8,csv23==0.2,execnet==1.7.1,freezegun==0.3.15,mock==4.0.2,more-itertools==8.2.0,pip==20.1.dev0,pluggy==0.13.1,pretend==1.0.9,py==1.8.1,pycparser==2.20,pytest==3.8.2,pytest-cov==2.8.1,pytest-forked==1.1.3,pytest-rerunfailures==6.0,pytest-timeout==1.3.4,pytest-xdist==1.27.0,python-dateutil==2.8.1,PyYAML==5.3.1,scripttest==1.3,setuptools==41.2.0,six==1.14.0,virtualenv==16.7.10,Werkzeug==0.16.0,wheel==0.34.2
python run-test-pre: PYTHONHASHSEED='1630556793'
python run-test-pre: commands[0] | python -c 'import shutil, sys; shutil.rmtree(sys.argv[1], ignore_errors=True)' /Users/jaraco/code/public/pypa/pip/tests/data/common_wheels
python run-test-pre: commands[1] | python /Users/jaraco/code/public/pypa/pip/tools/tox_pip.py wheel -w /Users/jaraco/code/public/pypa/pip/tests/data/common_wheels -r /Users/jaraco/code/public/pypa/pip/tools/requirements/tests-common_wheels.txt
Collecting setuptools>=40.8.0
  Using cached setuptools-46.1.3-py3-none-any.whl (582 kB)
  Saved ./tests/data/common_wheels/setuptools-46.1.3-py3-none-any.whl
Collecting wheel
  Using cached wheel-0.34.2-py2.py3-none-any.whl (26 kB)
  Saved ./tests/data/common_wheels/wheel-0.34.2-py2.py3-none-any.whl
Skipping setuptools, due to already being wheel.
Skipping wheel, due to already being wheel.
python run-test: commands[0] | pytest --timeout 300
============================= test session starts ==============================
platform darwin -- Python 3.8.1, pytest-3.8.2, py-1.8.1, pluggy-0.13.1
rootdir: /Users/jaraco/code/public/pypa/pip, inifile: setup.cfg
plugins: timeout-1.3.4, rerunfailures-6.0, forked-1.1.3, cov-2.8.1, xdist-1.27.0
timeout: 300.0s
timeout method: signal
timeout func_only: False
collected 1533 items / 7 errors

==================================== ERRORS ====================================
_______________ ERROR collecting tests/functional/test_freeze.py _______________
tests/functional/test_freeze.py:175: in <module>
    def test_freeze_svn(script, tmpdir):
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
______________ ERROR collecting tests/functional/test_install.py _______________
tests/functional/test_install.py:272: in <module>
    def test_basic_install_editable_from_svn(script):
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
____________ ERROR collecting tests/functional/test_install_reqs.py ____________
tests/functional/test_install_reqs.py:116: in <module>
    def test_multiple_requirements_files(script, tmpdir):
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
____________ ERROR collecting tests/functional/test_install_user.py ____________
tests/functional/test_install_user.py:28: in <module>
    class Tests_UserSite:
tests/functional/test_install_user.py:48: in Tests_UserSite
    def test_install_subversion_usersite_editable_with_distribute(
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
_____________ ERROR collecting tests/functional/test_uninstall.py ______________
tests/functional/test_uninstall.py:325: in <module>
    def test_uninstall_editable_from_svn(script, tmpdir):
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
___________ ERROR collecting tests/functional/test_uninstall_user.py ___________
tests/functional/test_uninstall_user.py:8: in <module>
    from tests.functional.test_install_user import _patch_dist_in_site_packages
<frozen importlib._bootstrap>:991: in _find_and_load
    ???
<frozen importlib._bootstrap>:975: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:655: in _load_unlocked
    ???
<frozen importlib._bootstrap>:618: in _load_backward_compatible
    ???
.tox/python/lib/python3.8/site-packages/_pytest/assertion/rewrite.py:290: in load_module
    six.exec_(co, mod.__dict__)
tests/functional/test_install_user.py:28: in <module>
    class Tests_UserSite:
tests/functional/test_install_user.py:48: in Tests_UserSite
    def test_install_subversion_usersite_editable_with_distribute(
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
___________________ ERROR collecting tests/unit/test_vcs.py ____________________
tests/unit/test_vcs.py:415: in <module>
    def test_subversion__call_vcs_version():
tests/lib/__init__.py:1112: in need_svn
    return pytest.mark.svn(need_executable(
tests/lib/__init__.py:1081: in wrapper
    subprocess.check_output(check_cmd)
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:411: in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py:512: in run
    raise CalledProcessError(retcode, process.args,
E   subprocess.CalledProcessError: Command '('svn', '--version')' returned non-zero exit status 72.
------------------------------- Captured stderr --------------------------------
svn: error: Failed to locate 'svn'.
svn: error: The subversion command line tools are no longer provided by Xcode.
=========================== short test summary info ============================
ERROR tests/functional/test_freeze.py
ERROR tests/functional/test_install.py
ERROR tests/functional/test_install_reqs.py
ERROR tests/functional/test_install_user.py
ERROR tests/functional/test_uninstall.py
ERROR tests/functional/test_uninstall_user.py
ERROR tests/unit/test_vcs.py
!!!!!!!!!!!!!!!!!!! Interrupted: 7 errors during collection !!!!!!!!!!!!!!!!!!!!
=========================== 7 error in 7.96 seconds ============================
ERROR: InvocationError for command /Users/jaraco/code/public/pypa/pip/.tox/python/bin/pytest --timeout 300 (exited with code 2)
___________________________________ summary ____________________________________
ERROR:   python: commands failed