require that sanity_pip_check is enabled in new/changed easyconfigs

[boegel]

Support for running pip check during the sanity check to ensure that all required Python packages are installed was added in EasyBuild v4.1.0 (see #1853).

We should start requiring it in contributed easyconfigs, since it can prevent shipping broken easyconfigs (see #9306 for example).

You can enable the running of pip check either via:

sanity_pip_check = True

or

exts_default_options = {'sanity_pip_check': True}

(it can also be enabled for individual extensions, but there's little point in doing that imho, so no need to cover that in the check here)

[Flamefire]

Great! But we should also fix easybuilders/easybuild-easyblocks#1877 to avoid failures due to python using the user home.

[boegel]

easybuilders/easybuild-easyblocks#1877 is being fixed with easybuilders/easybuild-easyblocks#1891

@smoors This is good to go imho...

[Flamefire]

Thanks, LGTM. However I suggest to rework the assert messages (for pretty much all tests). The current one here is e.g. "sanity_pip_check is enabled in X". So if you see the test failing on travis this will be what is printed. The problem: The opposite is the case: The check failed because it is not enabled. This made me loose some time chasing for the failure because I couldn't understand the message. Better: "sanity_pip_check should be enabled in X" or "sanity_pip_check is not enabled in X"

[smoors]

@Flamefire I understand your confusion, but all other error messages are constructed in the same way.
So maybe file an issue on that?

[smoors]

lgtm

[Flamefire]

Ok: #9542

[smoors]

Test report by @smoors
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
login2.cerberus.os - Linux centos linux 7.6.1810, Intel(R) Xeon(R) Gold 6126 CPU @ 2.60GHz, Python 2.7.5
See https://gist.github.com/c8ff78e72b7d37aa98ea8d20075fff7f for a full test report.

[smoors]

Going in, thanks @boegel!