Confirmed:

$ PIP_REQUIRE_VIRTUALENV=true ./python -m test test_venv
[1/1] test_venv
test test_venv failed -- Traceback (most recent call last):
  File "/home/ncoghlan/devel/py3k/Lib/test/test_venv.py", line 298, in test_with_pip
    self.run_with_capture(venv.create, self.env_dir, with_pip=True)
subprocess.CalledProcessError: Command '['/tmp/tmpo1fj4gy6/bin/python', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 3

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/ncoghlan/devel/py3k/Lib/test/test_venv.py", line 304, in test_with_pip
    self.fail(msg)
AssertionError: Command '['/tmp/tmpo1fj4gy6/bin/python', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 3

**Subprocess Output**
Could not find an activated virtualenv (required).


1 test failed:
    test_venv