[BUG] 1.8.0: pytest is failing in 5 units

Describe your issue.

Looks lik epytest is failing in few units.

Reproducing Code Example

I'm trying to package your module as an rpm package. So I'm using the typical PEP517 based build, install and test cycle used on building packages from non-root account.
- `python3 -sBm build -w --no-isolation`
- because I'm calling `build` with `--no-isolation` I'm using during all processes only locally installed modules
- install .whl file in </install/prefix>
- run pytest with PYTHONPATH pointing to sitearch and sitelib inside </install/prefix>

Error message

will include in next comment.

SciPy/NumPy/Python version information

scipy 1.8.0, python 3.8.13

[ev-br]

$ python dev.py or $ python runtests.py from the scipy root. Or, $ pytest --pyargs scipy to test already-installed version away from the repo root folder.

[rgommers]

The first failure is from a test using subprocess.check_call([sys.executable, '-c', TEST_BODY]). So it runs into exactly the failure mode you apparently already understand. The output really cannot be clearer:

ImportError: Error importing SciPy: you cannot import SciPy while
        being in scipy source directory; please exit the SciPy source
        tree first and relaunch your Python interpreter.

There’s only one way to get that output, which is running tests from the root of the repo. This is wrong, no matter how you invoke pytest; that invocation method does not carry over to the fresh process created by subprocess.check_call it looks like.

Now it would be really nice if you actually confirmed that doing cd .. and rerunning the tests will make those failures go away. And by “really nice” I mean “you’re breaking open source etiquette by not even trying the solution that a maintainer has suggested to you”.